Correct Answer: D

Rationale: To divide fractions, you multiply the first fraction by the reciprocal of the second fraction. In this case, (2/7) · (5/6) becomes (2/7) (6/5) = 12/35. Therefore, the correct answer is 12/35. Choice A (2/5), choice B (35/15), and choice C (5/21) are incorrect because they do not correctly simplify the given expression.

Correct Answer: C

Rationale: To find the mean time, you need to add all the times (22.33 + 22.50 + 22.50 + 22.61 + 22.71 + 22.72 + 22.83 + 23.22) and then divide by the total number of times (8). This calculation results in a mean time of 22.68 seconds. Choice A, 22.50 sec, is incorrect because it is the time of one of the runners, not the mean time. Choice B, 22.66 sec, and Choice D, 22.77 sec, are also incorrect as they are not the calculated mean of the given times.

Correct Answer: D

Rationale: The mean number of vacuum cleaners sold per month is 31.7, the mode is 29, the median is 31, and the range is 29. The mode being equal to the range is the correct statement. Option A is incorrect because the mean (31.7) is greater than the median (31). Option B is incorrect as the mode (29) is not greater than the median (31). Option C is incorrect since the mode (29) is not less than the mean, median, or range.

Correct Answer: D

Rationale: To solve the equation for x, follow these steps: 2x - 7 = 3. Add 7 to both sides to isolate 2x, resulting in 2x = 10. Then, divide by 2 on both sides to find x, which gives x = 5. Therefore, the correct answer is x = 5. Choices A, B, and C are incorrect because they do not accurately solve the equation.

Correct Answer: C

Rationale: To find the surface area of a rectangular prism, you use the formula SA = 2lw + 2wh + 2hl, where l is the length, w is the width, and h is the height. Substituting the given dimensions, the calculation would be SA = 2(14)(6) + 2(6)(8) + 2(8)(14) = 168 + 96 + 224 = 488 square inches. Therefore, 488 square inches of wrapping paper are needed to wrap the box. Choice A (56), Choice B (244), and Choice D (672) are incorrect because they do not represent the correct surface area calculation for the given box dimensions.