Correct Answer: A

Rationale: First, calculate the total cost of the 20 stamps bought at 29¢ each: 20 stamps * 29¢ = $5.80. Next, calculate the total cost of the 40 stamps bought at 42¢ each: 40 stamps * 42¢ = $16.80. The total cost of all stamps is $5.80 + $16.80 = $22.60. If Tamison gave $25 to the postal worker, her change is $25 - $22.60 = $2.40. Therefore, the correct answer is A. Option B, C, and D are incorrect as they do not reflect the correct change Tamison received after buying the stamps.

Correct Answer: B

Rationale: If Gerald can bake 3 dozen cookies in 30 minutes, then he can bake 1 dozen cookies in 10 minutes (30 minutes / 3 = 10 minutes). To bake 12 dozen cookies, it would take him 120 minutes (12 dozen x 10 minutes = 120 minutes), which is equivalent to 1 hour and 40 minutes. Choice A (90 minutes) is incorrect because it does not account for the correct proportion of cookies baked. Choice C (2 hours) and Choice D (4 hours) are incorrect as they overestimate the time required based on the given information.

Correct Answer: A

Rationale: To express the ratio 25:80 as a percentage, follow these steps: First, divide 25 by 80: 25/80 = 0.3125. Then, multiply by 100 to convert to a percentage: 0.3125 100 = 31.25%. Therefore, the ratio 25:80 is equivalent to 31.25%. Choice A is correct. Choice B (34%) is incorrect because it does not accurately represent the ratio 25:80. Choice C (41.25%) and Choice D (43.75%) are also incorrect as they do not match the calculated percentage for the given ratio.

Correct Answer: B

Rationale: The ratio given is 6:16, which can be simplified to 3:8 by dividing both sides by 2. This means that for every 3 surfers, there are 8 swimmers. To find a possible number of surfers and swimmers that fit this ratio, we can multiply both parts of the ratio by a common factor. Multiplying 3 and 8 by 24 gives us 72 surfers and 210 swimmers, which makes answer choice B the correct option. Choice A, C, and D do not reflect the ratio of surfers to swimmers given in the question.

Correct Answer: B

Rationale: To find the number that 15 is 20% of, we set up the equation: x * 0.20 = 15. Solving for x, we get x = 15 / 0.20 = 75. Therefore, 15 is 20% of 75. Choice A, 3, is too small to be 20% of 15. Choice C, 75, is the result of the correct calculation. Choice D, 300, is too large to be 20% of 15.