Correct Answer: A

Rationale: To multiply fractions, multiply the numerators together and the denominators together. In this case, 3/4 1/3 = (3 1) / (4 3) = 3/12 = 1/4. Therefore, the correct answer is A: 1/4. Choices B (1/3), C (3/5), and D (3/8) are incorrect because they do not result from the correct multiplication of the given fractions.

Correct Answer: B

Rationale: To determine how many nurses are needed for 25 patients, set up a proportion: 3 nurses / 15 patients = x nurses / 25 patients. Cross multiply to solve for x: 3 * 25 = 15 * x. This simplifies to 75 = 15x. Divide both sides by 15 to find x = 5. Therefore, 5 nurses are needed for 25 patients. Choices A, C, and D are incorrect as they do not correspond to the correct calculation based on the given proportion.

Correct Answer: B

Rationale: To find the sum of fractions with the same denominator, add the numerators. Here, 3/7 + 4/7 + 2/7 = (3 + 4 + 2)/7 = 9/7. Therefore, the correct answer is 9/7. Choice A (7/7) is incorrect as the sum is not 7/7. Choice C (6/7) is incorrect as the sum is not 6/7. Choice D (7/7) is incorrect as the sum is not 7/7.

Correct Answer: C

Rationale: To find the divisor, you need to divide the dividend by the quotient. In this case, the dividend is 12 and the quotient is 4. Dividing 12 by 4 gives you the divisor, which is 3. Therefore, the correct answer is 4. Choices A, B, and D are incorrect because they do not result from dividing the dividend by the quotient in this scenario.

Correct Answer: B

Rationale: To find the rate of calories burned per mile, divide the total calories burned by the total miles run: 2276 · 21.4 ≈ 106.4 calories per mile. This calculation gives the average number of calories burned for each mile of the marathon. Choice A, 107.5, is incorrect as it does not match the precise calculation result. Choices C and D are also incorrect as they are not the accurate rate of calories burned per mile based on the given data.