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question:A scout troop buys 1500 candy bars priced at three for 1.50. They sell all the candy bars at the price of three for 2. What was their profit, in dollars? textbf{(A)} 200.5 qquad textbf{(B)} 225.5 qquad textbf{(C)} 250.5 qquad textbf{(D)} 275.5 qquad textbf{(E)} 300.5
answer:1. **Calculate the cost price of the candy bars:** The troop buys candy bars at a rate of 3 bars for 1.50. Therefore, the cost per bar is: [ frac{1.50 text{ dollars}}{3 text{ bars}} = 0.5 text{ dollars per bar} ] Since they buy 1500 bars, the total cost is: [ 1500 text{ bars} times 0.5 text{ dollars per bar} = 750 text{ dollars} ] 2. **Calculate the selling price of the candy bars:** The troop sells the candy bars at a rate of 3 bars for 2. Therefore, the selling price per bar is: [ frac{2 text{ dollars}}{3 text{ bars}} = 0.667 text{ dollars per bar} ] Since they sell 1500 bars, the total revenue is: [ 1500 text{ bars} times 0.667 text{ dollars per bar} = 1000.5 text{ dollars} ] 3. **Calculate the profit:** The profit is the difference between the total revenue and the total cost: [ text{Profit} = text{Total Revenue} - text{Total Cost} = 1000.5 text{ dollars} - 750 text{ dollars} = 250.5 text{ dollars} ] Thus, the scout troop's profit is 250.5 dollars. The final answer is boxed{textbf{(C)} 250.5}
question:Let S be the set of all rational numbers r, 0<r<1, that have a repeating decimal expansion in the form 0.defdefdefldots=0.overline{def}, where the digits d, e, and f are not necessarily distinct. To write the elements of S as fractions in lowest terms, how many different numerators exist if d+e+f is not divisible by 3?
answer:Consider a repeating decimal x = 0.overline{def}. Convert to fraction: x = 0.overline{def} 1000x = def.overline{def} 999x = 1000x - x = def x = frac{def}{999} If def (as a number) is not divisible by factors of 999 that are not 3, the fraction is in its lowest terms. We are given that d+e+f is not divisible by 3, hence def is not divisible by 3. The factors of 999 are 3^3 and 37, but the condition d+e+f not divisible by 3 ensures the fraction frac{def}{999} can't be reduced by 3. We need to consider 37: - Total possible values for def from 001 to 999 are 999. - Values divisible by 37 are 27 multiples. - Thus, numbers not divisible by 37 are 999 - 27 = 972. Since each valid def not divisible by 37 yields a unique numerator: boxed{972}
question:the xycoordinate system, there are two points (m, n) and (m + 5, n + 2.5) on the line with the equation x = 2y + 5. What is the ycoordinate of the first point?
answer:Given the line equation x = 2y + 5, we can substitute the x and y coordinates of the first point (m, n) into the equation to find the y-coordinate (n). So, we have: m = 2n + 5 We don't have the exact values of m and n, but we can use the information about the second point (m + 5, n + 2.5) to find n. Since the second point lies on the same line, it must also satisfy the line equation. Therefore, we can substitute the x and y coordinates of the second point into the line equation: m + 5 = 2(n + 2.5) + 5 Now, let's solve for n: m + 5 = 2n + 5 + 5 m + 5 = 2n + 10 Since we know from the first point that m = 2n + 5, we can substitute this into the equation: 2n + 5 + 5 = 2n + 10 2n + 10 = 2n + 10 This equation is true for all values of n, which means that any value of n that satisfies the first point's equation (m = 2n + 5) will also satisfy the second point's equation. Therefore, to find the y-coordinate (n) of the first point, we can rearrange the first point's equation: m = 2n + 5 m - 5 = 2n (m - 5)/2 = n Since we don't have the exact value of m, we cannot determine the exact value of n. However, the y-coordinate of the first point (n) can be expressed in terms of m as (m - boxed{5)/2} .
question:a mathematics competition, the probability of student A solving a problem is frac{1}{2}, the probability of student B solving it is frac{1}{3}, and the probability of student C solving it is frac{1}{4}. What is the probability that, among students A, B, and C, who solve the problem independently, only one of them solves it?
answer:To determine the probability of only one student solving the problem, we need to consider the following mutually exclusive events: - Student A solves the problem, but students B and C do not. - Student B solves the problem, but students A and C do not. - Student C solves the problem, but students A and B do not. Given that the events of each student solving the problem are independent of each other, we can calculate the required probability as follows: For student A solving and others not solving: - Probability that A solves the problem: frac{1}{2}. - Probability that B does not solve the problem: 1 - frac{1}{3} = frac{2}{3}. - Probability that C does not solve the problem: 1 - frac{1}{4} = frac{3}{4}. - Combined probability for this scenario: frac{1}{2} times frac{2}{3} times frac{3}{4}. Similarly, we can calculate for B and C: - For B: frac{1}{2} times frac{1}{3} times frac{3}{4}. - For C: frac{1}{2} times frac{2}{3} times frac{1}{4}. Adding all the scenarios together, the required probability is: P(text{only one solves}) = left(frac{1}{2} times frac{2}{3} times frac{3}{4}right) + left(frac{1}{2} times frac{1}{3} times frac{3}{4}right) + left(frac{1}{2} times frac{2}{3} times frac{1}{4}right). Carrying out the calculation by multiplying the fractions and then performing the sum: P(text{only one solves}) = left(frac{1}{2} times frac{2}{3} times frac{3}{4}right) + left(frac{1}{2} times frac{1}{3} times frac{3}{4}right) + left(frac{1}{2} times frac{2}{3} times frac{1}{4}right) = left(frac{6}{24}right) + left(frac{3}{24}right) + left(frac{2}{24}right) = frac{11}{24}. Therefore, the probability that only one of the three students solves the problem is boxed{frac{11}{24}}.