A commuter survey counts the people riding in cars on a highway in the morning. Each car contains only one man, only one woman, or both one man and one woman. Out of 25 cars, 13 contain a woman and 20 contain a man. How many contain both a man and a woman?

Correct Answer: C

Rationale: Let's denote the number of cars containing only a man as M, only a woman as W, and both a man and a woman as B. Given that there are 25 cars in total, we have: M + W + B = 25 From the information provided, we know that 13 cars contain a woman (W) and 20 cars contain a man (M). Since each car contains either one man, one woman, or both, the cars that contain both a man and a woman (B) are counted once in each of the M and W categories. Therefore, to find out how many cars contain both a man and a woman, we need to subtract the number of cars that contain only a man and only a woman from the total cars. M + B = 20 (as 20 cars contain a man) W + B = 13 (as 13 cars contain a woman) Solving the above two equations simultaneously, we get: M = 12, W = 5, B = 8 Therefore, 8 cars contain both a man and a woman. Hence, the correct answer is 8. Choice A, B, and D are incorrect as they do not reflect the correct calculation based on the information provided.

Correct Answer: C

Rationale: When reducing a figure by a scale factor, each dimension is multiplied by the same scale factor. In this case, the scale factor is not provided in the question. To find the scale factor, you would divide the new lengths of the sides by the original lengths. The scaled-down triangle's dimensions are the original dimensions multiplied by the scale factor. By performing the calculations, the dimensions of the dilated triangle are 6.75 cm, 3 cm, and 5.25 cm, which matches choice C. Choices A, B, and D have incorrect dimensions as they do not result from the correct application of the scale factor to the original triangle's dimensions.

Correct Answer: B

Rationale: To find the least number of computers that must be shipped and sold so that the amount received is at least equal to the shipping cost, we set up the inequality 400x >= 3000 + 100x. Simplifying this inequality gives 300x >= 3000, and dividing by 300 results in x >= 10. Therefore, at least 15 computers must be shipped and sold to cover the shipping cost, making choice B the correct answer. Choices A, C, and D are incorrect as they represent numbers less than 15, which would not cover the shipping cost.

Correct Answer: A

Rationale: The cost for making g glasses of lemonade includes the initial cost of the stand ($45) plus 10¢ for each glass of lemonade sold. Therefore, the expression that represents the cost for making g glasses of lemonade is $45 + $0.1 g, which matches option A. Choice B, $44.90 g, is incorrect as it does not account for the initial stand cost of $45. Choice C, $44.90 g + 10¢, is incorrect because it does not include the initial stand cost and incorrectly adds an extra 10¢ for every glass. Choice D, $90, is incorrect as it does not consider the variable cost of 10¢ per glass and only represents the initial stand cost.

Correct Answer: D

Rationale: To determine the breakeven point where Truck B becomes the better buy, we need to compare the total costs for both trucks. For Truck A: Total cost = $450 + (miles / 25) * $4. For Truck B: Total cost = $650 + (miles / 35) * $4. To find the point where Truck B is the better buy, set the two total cost equations equal to each other and solve for miles. By solving this equation, we find that Sally must drive 4375 miles for Truck B to be the better buy. Choice A (500) is too low, Choice B (7500) is too high, and Choice C (1750) does not represent the breakeven point where Truck B becomes more cost-effective.