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❓:A design blogger is reviewing three different e-cigarette designs, each having a unique shape and aesthetic appeal. The designs are evaluated based on three criteria: battery life (B), vapor production (V), and design aesthetics (D). The blogger assigns a score from 0 to 10 for each criterion, and the overall score (S) for each e-cigarette is calculated using the following weighted formula:[ S = 0.4B + 0.3V + 0.3D ]Sub-problem 1:The blogger reviews the first e-cigarette design and assigns scores of B = 8, V = 7, and D = 9. Calculate the overall score for the first e-cigarette design using the given formula.Sub-problem 2:Assume the blogger wants to ensure that all reviewed e-cigarette designs have an overall score of at least 7. Given that the scores for the second e-cigarette design are B = 6 and D = 8, determine the minimum score for vapor production (V) needed to meet the blogger's criteria.
🧠:<think>First, I'll tackle Sub-problem 1 by calculating the overall score for the first e-cigarette design. The given scores are B = 8, V = 7, and D = 9. Using the formula S = 0.4B + 0.3V + 0.3D, I'll substitute the values:S = 0.4 * 8 + 0.3 * 7 + 0.3 * 9Calculating each term:0.4 * 8 = 3.20.3 * 7 = 2.10.3 * 9 = 2.7Adding these together:3.2 + 2.1 + 2.7 = 8.0So, the overall score for the first e-cigarette design is 8.0.Next, for Sub-problem 2, the blogger requires an overall score of at least 7 for the second e-cigarette design. The known scores are B = 6 and D = 8. I'll set up the equation:7 ≤ 0.4 * 6 + 0.3 * V + 0.3 * 8Calculating the known values:0.4 * 6 = 2.40.3 * 8 = 2.4Substituting these into the equation:7 ≤ 2.4 + 0.3V + 2.4Combining the constants:7 ≤ 4.8 + 0.3VSubtracting 4.8 from both sides:2.2 ≤ 0.3VDividing both sides by 0.3:V ≥ 7.333...Since scores are given to one decimal place, the minimum score for vapor production needed is 7.3.</think>
❓:A Database Management Systems professor is studying the efficiency of query processing algorithms. She is analyzing a database with a set of ( n ) tables, each with a different number of records. The professor models the database as a graph ( G = (V, E) ) where each vertex represents a table and each edge represents a potential join operation between two tables. The weight of each edge ( (u, v) ) is given by the function ( w(u, v) = log(r_u times r_v) ), where ( r_u ) and ( r_v ) are the number of records in tables ( u ) and ( v ) respectively.1. Formulate an equation to determine the minimum spanning tree (MST) of the graph ( G ). Explain how finding the MST relates to optimizing the execution of a series of join operations across the tables. 2. Given that the database is queried frequently, the professor wants to ensure robustness in the face of potential node failures. Suppose a table ( t in V ) is removed from the database graph ( G ). Prove or disprove that the remaining graph ( G' = (V setminus {t}, E') ) with edges ( E' subset E ) can be restructured to maintain the same minimum spanning tree weight by only removing edges incident to ( t ) and re-evaluating the MST for ( G' ).
🧠:<think>Okay, so I have this problem about a professor studying database query processing efficiency. She's modeling the database as a graph where each table is a vertex and each edge represents a potential join operation. The weight of each edge is the logarithm of the product of the number of records in the two tables it connects. Part 1 asks me to formulate an equation for the minimum spanning tree (MST) of this graph and explain how finding the MST relates to optimizing join operations. Hmm, I remember that an MST is a subset of edges that connects all the vertices with the minimum possible total edge weight, without any cycles. So, in this context, the MST would represent the optimal way to join all the tables with the least total cost, where the cost is based on the logarithm of the product of their record counts.Wait, the weight is log(r_u * r_v). Since log(a*b) is log(a) + log(b), that means each edge's weight is the sum of the logs of the records in each table. So, when we sum all the edge weights in the MST, it's equivalent to summing log(r_u) + log(r_v) for each edge. But since each table is connected in the MST, each log(r_u) will appear exactly (degree of u) times. But in a tree, the sum of degrees is 2(n-1), so each log(r_u) is counted twice? Wait, no, because each edge connects two tables, so each log(r_u) is added once for each edge it's part of. But in the MST, each table is connected exactly once, except for the root, which is connected once as well. Wait, actually, in a tree with n nodes, there are n-1 edges. So each edge contributes log(r_u) + log(r_v). So the total weight is the sum over all edges in MST of (log(r_u) + log(r_v)).But let me think about this. If I have an MST, the total weight is the sum of log(r_u * r_v) for each edge. So that's the same as sum(log(r_u) + log(r_v)) for each edge. So that's equivalent to sum(log(r_u) * degree(u)) for all u, but since each edge contributes two terms, the total sum is equal to 2 * sum(log(r_u)) for all u in the MST. Wait, no, because each edge is counted once, but each log(r_u) is added for each edge it's part of. So if a table u has degree d in the MST, then log(r_u) is added d times. So the total weight is sum_{u in V} (d_u * log(r_u)), where d_u is the degree of u in the MST.But since the MST is a tree, the sum of degrees is 2(n-1). So the total weight is sum_{u in V} (d_u * log(r_u)) = sum_{edges} (log(r_u) + log(r_v)).But how does this relate to optimizing join operations? Well, in databases, joining two tables can be expensive, especially if the tables are large. The cost of a join is often proportional to the product of the sizes of the two tables. So, if we have multiple joins, the total cost would be the sum of the costs of each individual join. But in this model, the weight is log(r_u * r_v), which is the logarithm of the product. So, the total weight of the MST is the sum of log(r_u * r_v) for all edges in the MST. Since log is a monotonically increasing function, minimizing the sum of logs is equivalent to minimizing the product of the original values. So, the MST minimizes the product of (r_u * r_v) over all edges in the tree. Therefore, finding the MST in this graph would give the optimal sequence of joins that minimizes the total cost, assuming the cost is proportional to the product of the sizes of the tables being joined. So, the MST represents the most efficient way to join all tables with the least computational cost.Moving on to part 2. The professor wants to ensure robustness against node failures. If a table t is removed, we need to see if the remaining graph G' can maintain the same MST weight by only removing edges incident to t and re-evaluating the MST. Hmm, so if we remove a node t, we also remove all edges connected to t. Then, we need to check if the MST of G' has the same total weight as the original MST minus the edges connected to t.Wait, but the original MST included edges connected to t. So, if we remove t, we have to find a new MST for G' which doesn't include t. The question is whether the weight of this new MST is equal to the original MST's weight minus the sum of the weights of the edges incident to t in the original MST.But is that necessarily true? Let me think. Suppose in the original MST, node t had degree k. So, the original MST had k edges connected to t. If we remove t and those k edges, the remaining graph G' has n-1 nodes and the original MST minus those k edges. But G' might not be connected anymore because we removed t and its incident edges. So, to form an MST for G', we might need to add some new edges to reconnect the components.Therefore, the weight of the new MST could be different. It might be higher because we have to add edges that weren't in the original MST, which could have higher weights. Alternatively, if the original MST had some edges that were not necessary for connectivity, maybe the new MST could have the same weight? Hmm, not sure.Wait, let's think with an example. Suppose we have a simple graph with three nodes: A, B, C. Suppose the edges are AB with weight 1, AC with weight 2, and BC with weight 3. The MST would be AB and AC, total weight 3. Now, if we remove node C, the remaining graph has nodes A and B connected by edge AB with weight 1. So, the MST of G' is just AB with weight 1, which is less than the original MST weight of 3 minus the edges connected to C, which was AC with weight 2. So, 3 - 2 = 1, which matches. So in this case, it works.But let's try another example. Suppose we have four nodes: A, B, C, D. The edges are AB:1, AC:2, AD:3, BC:4, BD:5, CD:6. The MST would be AB, AC, AD with total weight 6. Now, if we remove node D, the remaining graph has nodes A, B, C. The MST of G' would be AB and AC, total weight 3. The original MST had AD with weight 3, so 6 - 3 = 3, which matches. So again, it works.Wait, but what if the original MST had a structure where removing a node disconnects the graph into multiple components, and the new MST requires adding edges that are not in the original MST? Let's see. Suppose we have a graph where node t is a central hub connected to all other nodes. For example, node t connected to A, B, C with edges of weights 1, 2, 3. And there are no other edges between A, B, C. So the MST would be t connected to A, B, C, total weight 6. Now, if we remove t, the remaining graph has nodes A, B, C with no edges. So, to form an MST, we need to add edges between them. But since there are no edges, it's impossible. So, the graph becomes disconnected, and there is no MST. So, in this case, the remaining graph G' is disconnected, so it doesn't have an MST. Therefore, the statement is false because G' might not even have an MST if it's disconnected.But wait, the problem says "the remaining graph G' can be restructured to maintain the same minimum spanning tree weight by only removing edges incident to t and re-evaluating the MST for G'." So, if G' is disconnected, it can't have an MST. Therefore, the statement is false because removing t might disconnect G', making it impossible to have an MST.Alternatively, if G' remains connected after removing t and its incident edges, does the MST weight equal the original MST weight minus the sum of the edges incident to t in the original MST? Let's test this.Take the earlier example with four nodes. If we remove D, the remaining graph is connected, and the MST weight is 3, which is 6 - 3. So, it works. But if we have a different structure where removing t doesn't disconnect the graph, does it hold?Suppose we have a cycle: A-B-C-A, with edges AB:1, BC:2, CA:3. The MST would be AB and BC, total weight 3. If we remove node C, the remaining graph has nodes A and B connected by AB with weight 1. The original MST had BC with weight 2, so 3 - 2 = 1, which matches. So, it works here too.But what if the original MST had a node t that was a leaf, and removing it doesn't affect the rest. For example, in a chain A-B-C-D, with edges AB:1, BC:2, CD:3. The MST is the entire chain, total weight 6. If we remove D, the remaining graph is A-B-C, with edges AB:1, BC:2. The MST is AB and BC, total weight 3. The original MST had CD:3, so 6 - 3 = 3, which matches.But what if the original MST has a node t that is part of a more complex structure? Suppose we have a graph where t is connected to A and B, and A is connected to B with a higher weight. For example, edges tA:1, tB:2, AB:3. The MST would be tA and tB, total weight 3. If we remove t, the remaining graph has nodes A and B connected by AB with weight 3. The original MST had tA and tB, total weight 3. So, the new MST is AB with weight 3, which is the same as the original MST weight. So, in this case, the weight remains the same, but the edges are different.Wait, so the total weight is the same, but the edges are different. So, the weight is maintained, but the structure changes. So, in this case, the statement holds because the weight is the same, even though the edges are different.But in the earlier example where removing t disconnects the graph, the statement fails because there is no MST. So, the answer depends on whether G' remains connected after removing t and its incident edges.But the problem doesn't specify that G' remains connected. It just says "the remaining graph G' can be restructured to maintain the same minimum spanning tree weight by only removing edges incident to t and re-evaluating the MST for G'." So, if G' is disconnected, it can't have an MST, so the statement is false.Alternatively, if G' remains connected, then the MST weight is the original MST weight minus the sum of the edges incident to t in the original MST. But wait, in the example where t was connected to A and B, and A and B were connected by a higher weight edge, the original MST had tA and tB, total weight 3. After removing t, the MST of G' is AB with weight 3, which is the same as the original MST weight. So, in this case, the weight is maintained, but the edges are different.But in another example, suppose t is connected to A with weight 1, and A is connected to B with weight 2, and B is connected to C with weight 3, and C is connected to t with weight 4. The MST would be tA, AB, BC, total weight 1+2+3=6. If we remove t, the remaining graph has A, B, C connected by AB and BC, total weight 5, which is less than 6. So, in this case, the MST weight decreases.Wait, but the original MST had tA (1), AB (2), BC (3). If we remove t, the remaining graph has edges AB (2), BC (3), and maybe AC if it exists. But in this case, the MST of G' is AB and BC, total weight 5, which is less than the original MST weight of 6. So, the weight decreases.But the problem statement says "maintain the same minimum spanning tree weight." So, in this case, it's not maintained; it's reduced. Therefore, the statement is false because sometimes the MST weight can decrease, not necessarily stay the same.Wait, but in the example where t was a leaf, the weight remained the same. So, it depends on the structure. Therefore, the statement is not always true. Hence, it's false.So, to summarize, removing a node t and its incident edges might disconnect the graph, making it impossible to have an MST. Even if it remains connected, the MST weight might not be the same as the original minus the edges incident to t. Therefore, the statement is false.</think>
❓:A dedicated volunteer organizes donation drives for refugee families. Each donation drive collects different types of essential items: food, clothing, and medical supplies. The volunteer wants to optimize the distribution of these items to maximize the benefit to the refugee families.1. The volunteer receives a total of ( F ) units of food, ( C ) units of clothing, and ( M ) units of medical supplies. The benefit function for a refugee family receiving ( x ) units of food, ( y ) units of clothing, and ( z ) units of medical supplies is given by ( B(x, y, z) = 3x^2 + 2y^2 + 5z^2 - 2xy - yz + xz ). Determine the optimal values of ( x ), ( y ), and ( z ) to maximize the benefit function ( B(x, y, z) ) for a single family, subject to the constraints ( x leq frac{F}{n} ), ( y leq frac{C}{n} ), and ( z leq frac{M}{n} ), where ( n ) is the number of refugee families.2. Suppose the volunteer wants to ensure that each family receives at least ( a ) units of food, ( b ) units of clothing, and ( c ) units of medical supplies. Given the constraints ( x geq a ), ( y geq b ), ( z geq c ), along with the previous constraints, formulate a linear programming problem to determine the maximum number of refugee families ( n ) that can be supported while still optimizing the benefit function ( B(x, y, z) ).
🧠:<think>Okay, so I have this problem about a volunteer organizing donation drives for refugee families. The goal is to optimize the distribution of food, clothing, and medical supplies to maximize the benefit function for each family. There are two parts to the problem. Let me try to tackle them one by one.Starting with part 1: The volunteer has F units of food, C units of clothing, and M units of medical supplies. The benefit function is given by B(x, y, z) = 3x² + 2y² + 5z² - 2xy - yz + xz. We need to find the optimal values of x, y, and z to maximize B, subject to the constraints x ≤ F/n, y ≤ C/n, and z ≤ M/n, where n is the number of families.Hmm, okay. So, first, I need to maximize this quadratic function B(x, y, z). Since it's a quadratic function, it might have a maximum or a minimum. Let me check the coefficients to see if it's concave or convex. The function is quadratic, so the Hessian matrix will tell me about its concavity.The Hessian matrix H is the matrix of second derivatives. Let's compute it.First, the first partial derivatives:dB/dx = 6x - 2y + zdB/dy = 4y - 2x - zdB/dz = 10z - y + xNow, the second partial derivatives:d²B/dx² = 6d²B/dy² = 4d²B/dz² = 10Cross partials:d²B/dxdy = -2d²B/dxdz = 1d²B/dydz = -1So, the Hessian matrix H is:[6 -2 1][-2 4 -1][1 -1 10]To determine if the function is concave or convex, I need to check if the Hessian is negative definite or positive definite. If it's negative definite, the function is concave, and we can find a maximum. If it's positive definite, it's convex, and we might have a minimum.To check if H is positive definite, we can check if all leading principal minors are positive.First minor: 6 > 0Second minor: determinant of top-left 2x2 matrix:|6 -2||-2 4| = (6)(4) - (-2)(-2) = 24 - 4 = 20 > 0Third minor: determinant of the full Hessian.Let me compute that.|6 -2 1||-2 4 -1||1 -1 10|Compute determinant:6*(4*10 - (-1)*(-1)) - (-2)*(-2*10 - (-1)*1) + 1*(-2*(-1) - 4*1)= 6*(40 - 1) - (-2)*( -20 + 1 ) + 1*(2 - 4)= 6*39 - (-2)*(-19) + 1*(-2)= 234 - 38 - 2= 234 - 40 = 194 > 0So all leading principal minors are positive, so H is positive definite. That means the function is convex, so it has a unique minimum, not a maximum. Hmm, that complicates things because we are supposed to maximize B(x, y, z). If the function is convex, it doesn't have a global maximum unless we're constrained within a compact set.Wait, the constraints are x ≤ F/n, y ≤ C/n, z ≤ M/n. So, the feasible region is a box in the positive orthant. Since the function is convex, the maximum will occur at one of the corners of the feasible region.So, to maximize B(x, y, z), we need to evaluate B at the corners of the feasible region defined by x = F/n, y = C/n, z = M/n. But wait, the corners would be all combinations of x = 0 or F/n, y = 0 or C/n, z = 0 or M/n. But since we are distributing to refugee families, x, y, z should be non-negative. So, the maximum would be at the point where x, y, z are as large as possible, i.e., x = F/n, y = C/n, z = M/n.But wait, is that necessarily the case? Because the function is convex, the maximum could be at the upper bounds. Let me think.Alternatively, perhaps I made a mistake in interpreting the problem. Maybe the function is actually concave? Wait, the Hessian is positive definite, so it's convex. So, the function tends to infinity as variables increase, but since we have upper bounds, the maximum would be at the upper bounds.Wait, but the function is quadratic, so it's convex, meaning that it curves upward. So, if we have constraints, the maximum would be at the boundaries. So, yes, the maximum would be achieved when x, y, z are as large as possible, i.e., x = F/n, y = C/n, z = M/n.But let me verify this. Let me plug in x = F/n, y = C/n, z = M/n into the benefit function and see if that's indeed the maximum.Alternatively, maybe the function can be rewritten in a way that shows it's convex. Let me see.Alternatively, perhaps I can set up the Lagrangian to maximize B(x, y, z) subject to the constraints x ≤ F/n, y ≤ C/n, z ≤ M/n, and x, y, z ≥ 0.But since the function is convex, the maximum will be at the boundary. So, the optimal solution is x = F/n, y = C/n, z = M/n.Wait, but let me check if that's the case. Suppose we have n=1, so x=F, y=C, z=M. Then, B(F, C, M) would be 3F² + 2C² + 5M² - 2FC - CM + FM.But if n increases, x, y, z decrease, so B would decrease because it's quadratic. So, for each family, the benefit is maximized when each family gets as much as possible, i.e., x=F/n, y=C/n, z=M/n.Wait, but maybe the function isn't separable, so perhaps distributing more to some families and less to others could yield a higher total benefit. But the problem is about maximizing the benefit for a single family, not the total benefit across all families.Wait, the problem says: "Determine the optimal values of x, y, and z to maximize the benefit function B(x, y, z) for a single family, subject to the constraints x ≤ F/n, y ≤ C/n, and z ≤ M/n, where n is the number of refugee families."So, for each family, we need to maximize B(x, y, z) given that x ≤ F/n, y ≤ C/n, z ≤ M/n.But since the function is convex, the maximum occurs at the upper bounds. So, x = F/n, y = C/n, z = M/n.Wait, but let me think again. If the function is convex, then it's U-shaped, so the maximum would be at the boundaries. So, yes, the maximum for each family would be at x = F/n, y = C/n, z = M/n.But wait, let me compute the gradient and see if at x = F/n, y = C/n, z = M/n, the gradient is pointing inward or outward.The gradient is [6x - 2y + z, 4y - 2x - z, 10z - y + x].At x = F/n, y = C/n, z = M/n, the gradient would be:6(F/n) - 2(C/n) + (M/n) = (6F - 2C + M)/n4(C/n) - 2(F/n) - (M/n) = (4C - 2F - M)/n10(M/n) - (C/n) + (F/n) = (10M - C + F)/nNow, if the gradient at this point is pointing inward, meaning that increasing x, y, z would decrease B, then this point is a maximum. But since the function is convex, the gradient at the maximum point should be zero or pointing outward.Wait, but if the function is convex, the minimum is achieved at the critical point, and the maximum is at the boundaries. So, the gradient at the boundaries might not be zero, but the function is maximized there.Wait, perhaps I should set up the Lagrangian with inequality constraints.Let me try that.The Lagrangian would be:L = 3x² + 2y² + 5z² - 2xy - yz + xz - λ1(x - F/n) - λ2(y - C/n) - λ3(z - M/n)But since we are maximizing, the KKT conditions would require that the gradient of L is zero, and the constraints are satisfied.But since the function is convex, the maximum is at the boundary, so we can assume that x = F/n, y = C/n, z = M/n.But let me check if the gradient is zero at that point.Compute the partial derivatives:dB/dx = 6x - 2y + zAt x = F/n, y = C/n, z = M/n:6(F/n) - 2(C/n) + (M/n) = (6F - 2C + M)/nSimilarly, dB/dy = 4y - 2x - z = (4C - 2F - M)/ndB/dz = 10z - y + x = (10M - C + F)/nFor the gradient to be zero, all these must be zero:6F - 2C + M = 04C - 2F - M = 010M - C + F = 0This system of equations would give us the critical point. Let me solve it.Equation 1: 6F - 2C + M = 0Equation 2: -2F + 4C - M = 0Equation 3: F - C + 10M = 0Let me write them as:1) 6F - 2C + M = 02) -2F + 4C - M = 03) F - C + 10M = 0Let me add equations 1 and 2:(6F - 2C + M) + (-2F + 4C - M) = 0 + 04F + 2C = 0 => 2F + C = 0 => C = -2FHmm, that's interesting. Let me plug C = -2F into equation 3:F - (-2F) + 10M = 0 => F + 2F + 10M = 0 => 3F + 10M = 0 => M = -3F/10Now, plug C = -2F and M = -3F/10 into equation 1:6F - 2*(-2F) + (-3F/10) = 06F + 4F - 3F/10 = 010F - 3F/10 = 0(100F - 3F)/10 = 0 => 97F/10 = 0 => F = 0Then, C = -2F = 0, M = -3F/10 = 0So, the only critical point is at F = C = M = 0, which is trivial. So, the function doesn't have a critical point in the positive orthant except at the origin. Therefore, the maximum must occur at the boundaries.Therefore, the optimal values are x = F/n, y = C/n, z = M/n.So, for part 1, the optimal values are x = F/n, y = C/n, z = M/n.Now, moving on to part 2: The volunteer wants to ensure each family receives at least a units of food, b units of clothing, and c units of medical supplies. So, we have constraints x ≥ a, y ≥ b, z ≥ c, along with x ≤ F/n, y ≤ C/n, z ≤ M/n.We need to formulate a linear programming problem to determine the maximum number of refugee families n that can be supported while still optimizing the benefit function B(x, y, z).Wait, but in part 1, we found that the optimal x, y, z are x = F/n, y = C/n, z = M/n. Now, with the additional constraints x ≥ a, y ≥ b, z ≥ c, we need to ensure that F/n ≥ a, C/n ≥ b, M/n ≥ c. Because x = F/n must be at least a, similarly for y and z.So, F/n ≥ a => n ≤ F/aSimilarly, n ≤ C/b and n ≤ M/cTherefore, the maximum n is the minimum of F/a, C/b, M/c.But wait, the problem says to formulate a linear programming problem. So, perhaps I need to set it up more formally.Let me define n as the number of families. We need to maximize n subject to:x = F/n ≥ a => n ≤ F/ay = C/n ≥ b => n ≤ C/bz = M/n ≥ c => n ≤ M/cAlso, since x, y, z must be non-negative, but since F, C, M are positive, and n is positive, this is already satisfied.So, the constraints are:n ≤ F/an ≤ C/bn ≤ M/cn ≥ 1 (since you can't have zero families)But to formulate it as a linear program, we can write:Maximize nSubject to:n ≤ F/an ≤ C/bn ≤ M/cn ≥ 1But this is a simple maximization problem with n being the variable, and the constraints are upper bounds on n. So, the maximum n is the minimum of F/a, C/b, M/c.But perhaps the problem expects a more formal LP setup, including variables and all.Alternatively, maybe the problem wants to consider the benefit function B(x, y, z) while ensuring the minimums a, b, c. But since in part 1, we found that the optimal x, y, z are F/n, C/n, M/n, which are also the maximum possible given n, and now we have to ensure that these are at least a, b, c. So, the constraints are F/n ≥ a, C/n ≥ b, M/n ≥ c, which can be rewritten as n ≤ F/a, n ≤ C/b, n ≤ M/c.Therefore, the maximum n is the minimum of F/a, C/b, M/c.So, the linear programming problem would be:Maximize nSubject to:n ≤ F/an ≤ C/bn ≤ M/cn ≥ 1But since n must be an integer (number of families), but the problem doesn't specify, so perhaps it's a continuous variable.Alternatively, perhaps the problem wants to express it in terms of x, y, z, n.Wait, maybe I need to include x, y, z as variables as well, subject to:x = F/ny = C/nz = M/nx ≥ ay ≥ bz ≥ cBut since x, y, z are determined by n, we can just write the constraints on n.Alternatively, perhaps the problem is to maximize n, given that x ≥ a, y ≥ b, z ≥ c, and x ≤ F/n, y ≤ C/n, z ≤ M/n.So, combining these, we have x ≥ a and x ≤ F/n => F/n ≥ a => n ≤ F/aSimilarly for y and z.So, the maximum n is the minimum of F/a, C/b, M/c.Therefore, the LP formulation would be:Maximize nSubject to:n ≤ F/an ≤ C/bn ≤ M/cn ≥ 1But perhaps more formally, with variables n, and constraints as above.Alternatively, if we need to include x, y, z, we can write:Maximize nSubject to:x = F/ny = C/nz = M/nx ≥ ay ≥ bz ≥ cn ≥ 1But since x, y, z are dependent on n, it's more of a mathematical program with constraints.But since the problem says "formulate a linear programming problem," which typically involves linear constraints and a linear objective. Here, the objective is to maximize n, which is linear. The constraints are n ≤ F/a, etc., which are linear in n. So, yes, it's a linear program.So, the LP is:Maximize nSubject to:n ≤ F/an ≤ C/bn ≤ M/cn ≥ 1And n is a real variable (assuming it can be fractional, but in reality, n must be integer, but the problem doesn't specify, so perhaps it's okay as a continuous variable).So, to summarize:Part 1: The optimal values are x = F/n, y = C/n, z = M/n.Part 2: The maximum n is the minimum of F/a, C/b, M/c, formulated as an LP with n as the variable and constraints n ≤ F/a, n ≤ C/b, n ≤ M/c, and n ≥ 1.Wait, but in part 2, the problem says "formulate a linear programming problem to determine the maximum number of refugee families n that can be supported while still optimizing the benefit function B(x, y, z)."So, perhaps we need to include the optimization of B(x, y, z) as part of the LP, but since in part 1, we found that the optimal x, y, z are F/n, C/n, M/n, which are also the maximum possible given n, and now we have to ensure that these are at least a, b, c. So, the constraints are F/n ≥ a, C/n ≥ b, M/n ≥ c, which can be rewritten as n ≤ F/a, n ≤ C/b, n ≤ M/c.Therefore, the LP is as I wrote before: maximize n subject to n ≤ F/a, n ≤ C/b, n ≤ M/c, and n ≥ 1.So, I think that's the answer.</think>
❓:An elder resident of Alphington, Victoria, Australia, has a garden that is a perfect circle with a radius of 20 meters. The resident wants to plant a circular flower bed in the center of the garden. The flower bed will have a radius that is exactly one-third of the garden's radius. 1. The resident decides to create a walking path around the flower bed, with the path being 2 meters wide. Calculate the area of the walking path.2. Additionally, the resident wants to install a sprinkler system that covers the entire garden except for the flower bed. If the sprinkler system distributes water uniformly at a rate of 5 liters per square meter per hour, determine how many liters of water are required to cover the garden (excluding the flower bed) for 3 hours.
🧠:<think>First, I'll determine the radius of the flower bed, which is one-third of the garden's radius. The garden has a radius of 20 meters, so the flower bed's radius is 20 divided by 3, approximately 6.6667 meters.Next, I'll calculate the area of the garden using the formula for the area of a circle, ( A = pi r^2 ). For the garden, this is ( pi times 20^2 = 400pi ) square meters.Then, I'll find the area of the flower bed using the same formula. With a radius of approximately 6.6667 meters, the area is ( pi times (6.6667)^2 ), which is about ( 44.4444pi ) square meters.To find the area of the walking path, I'll subtract the area of the flower bed from the total area of the garden. This gives ( 400pi - 44.4444pi = 355.5556pi ) square meters, which is approximately 1117.05 square meters.For the sprinkler system, the area to be covered is the same as the area of the garden excluding the flower bed, 355.5556π square meters. The sprinkler distributes water at a rate of 5 liters per square meter per hour. Over 3 hours, the total water required is ( 5 times 3 times 355.5556pi ), which equals ( 5333.333pi ) liters, approximately 16755.16 liters.</think>