Correct Answer: C

Rationale: Teresa collected 144 baseball cards in 8 months. To find the average number of cards collected per month, we divide the total number of cards by the total months: 144 cards · 8 months = 18 cards per month. Therefore, on average, Teresa has collected 18 baseball cards per month. Choice A (12), Choice B (16), and Choice D (22) are incorrect as they do not match the correct calculation based on the information provided in the question.

Correct Answer: D

Rationale: Adding the given numbers together: 34 + 4 + 234 = 272. The correct sum is 272. Choice A, 70.2, is incorrect as it does not reflect the accurate addition of the numbers. Choice B, 230.72, is incorrect as well. Choice C, 234.74, is also incorrect since the correct sum is 272, not 234.74.

Correct Answer: B

Rationale: To express the ratio 13:60 as a percentage, calculate the decimal form of the ratio by dividing 13 by 60: 13/60 ≈ 0.2167. Next, convert this decimal to a percentage by multiplying by 100: 0.2167 x 100 = 21.67%. Choice A, 19.50%, is incorrect as it does not accurately represent the ratio. Choice C, 25.50%, and Choice D, 31%, are also incorrect calculations of the percentage equivalent of the ratio 13:60.

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: C

Rationale: To find the sum of the digits of the number 72, you simply add the individual digits together: 7 + 2 = 9. Therefore, the sum of the digits is 9. Choice A (6), Choice B (5), and Choice D (7) are incorrect as they do not correctly sum up the individual digits of the number 72.