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❓:Jane's car averages 30 miles per gallon of gasoline, and Mike's car averages 15 miles per gallon of gasoline. Jane, Mike, and their friend Carl, whose car averages 20 miles per gallon, each drive 100 miles. What is the cars' combined rate of miles per gallon of gasoline?textbf{(A)} 37 qquad textbf{(B)} 38 qquad textbf{(C)} 39 qquad textbf{(D)} 40
🧠:<think>First, I need to calculate the total distance driven by Jane, Mike, and Carl. Each of them drives 100 miles, so the total distance is:[100 text{ miles} times 3 = 300 text{ miles}]Next, I'll determine the amount of gasoline each person uses for their 100-mile drive.- Jane's Gasoline Usage: [ frac{100 text{ miles}}{30 text{ miles per gallon}} = frac{10}{3} text{ gallons} ]- Mike's Gasoline Usage: [ frac{100 text{ miles}}{15 text{ miles per gallon}} = frac{20}{3} text{ gallons} ]- Carl's Gasoline Usage: [ frac{100 text{ miles}}{20 text{ miles per gallon}} = 5 text{ gallons} ]Now, I'll sum up the total gasoline used by all three:[frac{10}{3} text{ gallons} + frac{20}{3} text{ gallons} + 5 text{ gallons} = frac{30}{3} text{ gallons} + 5 text{ gallons} = 10 text{ gallons} + 5 text{ gallons} = 15 text{ gallons}]Finally, to find the combined miles per gallon (mpg), I'll divide the total distance by the total gasoline used:[frac{300 text{ miles}}{15 text{ gallons}} = 20 text{ miles per gallon}]</think>
❓:What is the value of [3^{2+4+6} - (3^2 + 3^4 + 3^6) + (3^2 cdot 3^4 cdot 3^6)?]textbf{(A)} 1062063 qquad textbf{(B)} 1062242 qquad textbf{(C)} 531441 qquad textbf{(D)} 1060863 qquad textbf{(E)} 531620
🧠:<think>First, simplify the exponent in the term (3^{2+4+6}):[2 + 4 + 6 = 12]Thus, the expression becomes:[3^{12} - (3^2 + 3^4 + 3^6) + (3^2 cdot 3^4 cdot 3^6)]Next, calculate each power of 3:[3^{12}, quad 3^2 = 9, quad 3^4 = 81, quad 3^6 = 729]Then, evaluate the product of powers:[3^2 cdot 3^4 cdot 3^6 = 3^{2+4+6} = 3^{12}]Substitute these values back into the expression:[3^{12} - (9 + 81 + 729) + 3^{12}]Calculate the sum inside the parentheses:[9 + 81 + 729 = 819]Now substitute and simplify:[3^{12} + 3^{12} - 819]Recognizing that (3^{12} = 531441), the expression simplifies to:[531441 + 531441 - 819 = 1062063 - 819 = 1062242]The value of the expression is (boxed{textbf{(B)} 1062242}).</think>
❓:In a math quiz competition, Liam, Noah, and Olivia competed against each other. Each contest between two contestants yields a winner and a loser with no ties. Liam won 6 games and lost 3 games. Noah won 4 games and lost 4 games. If Olivia lost 4 games, how many games did she win if each win gives 1 point and each contestant meets all others an equal number of times?textbf{(A)} 3quad textbf{(B)} 4quad textbf{(C)} 5quad textbf{(D)} 6quad textbf{(E)} 7
🧠:<think>First, we determine the total number of games each player participated in:- Liam won 6 games and lost 3 games, so he played a total of (6 + 3 = 9) games.- Noah won 4 games and lost 4 games, so he played a total of (4 + 4 = 8) games.- Since Olivia competes an equal number of times with each opponent, her total number of games must be 8 as well (from Noah's games).Next, we set up the total game environment:- Each game involves two players, so each game is counted twice when summing individual games.- Let (x) be the number of games Olivia won. Thus, Olivia played (x + 4) games. Since everyone plays the same number of games, we set this equal to Noah’s and Liam's: [ x + 4 = 9 text{ (from Liam's games)} ]Solving for Olivia's games:[x + 4 = 9][x = 9 - 4 = 5]Finally, we conclude:- Each contestant meets others three times each.- Olivia’s total score is (1) point per win times the number of games she won, calculated as (5) games. [ 5 text{ points} ]The final answer is (boxed{textbf{(C)} 5}).</think>
❓:All the roots of the polynomial z^5 - 15z^4 + Pz^3 + Qz^2 + Rz + 64 are positive integers. What is the value of Q?(A) -60 (B) -55 (C) -50 (D) -45 (E) -40
🧠:<think>To solve the problem, we need to determine the value of ( Q ) for the polynomial ( z^5 - 15z^4 + Pz^3 + Qz^2 + Rz + 64 ) where all roots are positive integers.1. Identify the Roots: - The sum of the roots is given by the coefficient of ( z^4 ), which is 15. - The product of the roots is given by the constant term, which is 64. - We need to find five positive integers that sum to 15 and multiply to 64. A suitable set of roots is ( 8, 4, 1, 1, 1 ).2. Calculate the Third Symmetric Sum: - The third symmetric sum ( s_3 ) is the sum of all products of the roots taken three at a time. - The products are calculated as follows: - Three 1s: ( 1 times 1 times 1 = 1 ) - Two 1s and an 8: ( 8 times 1 times 1 = 8 ) - Two 1s and a 4: ( 4 times 1 times 1 = 4 ) - One 8, one 4, and one 1: ( 8 times 4 times 1 = 32 ) - Summing these products: ( 1 + 8 + 4 + 32 = 45 ).3. Determine ( Q ): - The value of ( Q ) is the negation of the third symmetric sum, so ( Q = -45 ).Thus, the value of ( Q ) is ( boxed{D} ).</think>