Subtract 20.7 - 13.4.

Correct Answer: C

Rationale: The correct answer is 7.3. To subtract 13.4 from 20.7, you align the decimal points and subtract each place value: 0.7 - 0.4 = 0.3, and 2 - 1 = 1. Therefore, 20.7 - 13.4 = 7.3. Choices A, B, and D are incorrect because they do not provide the accurate result of this subtraction.

Correct Answer: C

Rationale: To convert 9/10 to a decimal, divide 9 by 10: 9 · 10 = 0.9. The correct answer is 0.9. Choice A (0.7) is incorrect as 7/10 is equal to 0.7. Choice B (0.8) is incorrect as 8/10 is equal to 0.8. Choice D (1) is incorrect as 10/10 would be equal to 1.

Correct Answer: C

Rationale: The correct answer is 2 liters. There are 1,000 milliliters in a liter. Therefore, 2,000 milliliters is equal to 2 liters. Choice A is incorrect because it incorrectly doubles the conversion. Choice B is incorrect as it represents the amount in milliliters, not liters. Choice D is a duplicate of choice A, which is incorrect.

Correct Answer: A

Rationale: The probability of getting a '1' on a six-sided die is 1 out of 6 possible outcomes, making it a 1/6 probability. Therefore, choice A is correct. Choices B, C, and D are incorrect because they do not represent the correct probability of rolling a '1' on a standard six-sided die.

Correct Answer: B

Rationale: The correct answer is B. When you subtract 7.25 from 14.5, you get 7.25. The difference between 14.5 and 7.25 is 7.25. Choices A, C, and D are incorrect. Choice A (7.15) is the result of incorrectly subtracting 14.5 - 7.25. Choice C repeats choice A, so it is also wrong. Choice D (7.5) is not the correct result of the subtraction provided in the question.

Correct Answer: B

Rationale: To find the sum of 1/3, 1/4, and 1/6, we need to first find a common denominator. The least common multiple of 3, 4, and 6 is 12. So, we rewrite the fractions with the common denominator: 1/3 = 4/12, 1/4 = 3/12, and 1/6 = 2/12. Adding these fractions together gives us 4/12 + 3/12 + 2/12 = 9/12, which simplifies to 3/4 or 1/2. Therefore, the correct answer is 1/2. Choice A (5/12) is incorrect because it does not represent the sum of the fractions given. Choices C (1/3) and D (1/4) are also incorrect as they are individual fractions and do not represent the sum of the fractions provided.

Correct Answer: C

Rationale: To solve for x, cross-multiply: x/250 = 3/500. This simplifies to x = 1.5. Therefore, the correct answer is 1.5. Choice A (150) is incorrect because it does not account for the division by 250. Choice B (25.5) is incorrect as it is not the correct result of the calculation. Choice D (60) is incorrect as it is not the correct result of the calculation either.

Correct Answer: A

Rationale: To find the total time taken, add the time for each segment: 1 hour + 1.2 hours + 1.5 hours + 1.6 hours = 5.3 hours. Therefore, it took her 5.3 hours to complete the course. The other choices are incorrect because they do not accurately reflect the cumulative time calculated based on the given information.

Correct Answer: A

Rationale: To add fractions, you need to find a common denominator. The common denominator for 8, 10, and 5 is 40. Then, convert each fraction: 7/8 = 35/40, 9/10 = 36/40, and 6/5 = 24/40. Now, add the fractions: 35/40 + 36/40 + 24/40 = 95/40, which simplifies to 2 15/40 or 2 3/8. Therefore, 7/8 + 9/10 + 6/5 = 3 & 39/40. Choice B is incorrect because it does not represent the correct addition of the fractions. Choice C is incorrect as it does not account for the whole number part. Choice D is incorrect as it is not the sum of the fractions and whole numbers.