Correct Answer: B

Rationale: To calculate the average speed, use the formula: Average speed = Total distance / Total time. In this case, Average speed = 150 miles / 3 hours = 50 mph. Therefore, the car's average speed is 50 miles per hour. Choice A (45 mph), Choice C (55 mph), and Choice D (60 mph) are incorrect as they do not match the correct calculation based on the given distance and time values.

Correct Answer: C

Rationale: If \(2x = 6\), then solving for \(x\), we have \(x = \frac{6}{2} = 3\). So, if \(x = 3\), then \(x+1 = 3+1 = 4\). Therefore, the value of \(x+1\) would be 4.

Correct Answer: C

Rationale: To determine the number of questions the student solved correctly, we need to calculate 85% of the total number of questions. This can be done by multiplying the total number of questions by 85%, which is 20 questions x 85% = 20 x 0.85 = 17 questions. Therefore, the student solved 17 questions correctly. Choice A, 15, is incorrect as it does not reflect the correct percentage of questions solved. Choice B, 16, and Choice D, 18, are also incorrect as they do not match the calculation based on the given percentage.

Correct Answer: A

Rationale: The relative error is calculated using the formula: (|Measured Value - True Value| / True Value) * 100%. Substituting the values given, we have (|36 - 75| / 75) * 100% = (39 / 75) * 100% ≈ 0.52 * 100% = 0.52%. Therefore, the relative error in measurement is approximately 0.52%. Choice A is correct because it reflects this calculation. Choice B is incorrect as it represents a lower relative error than the actual value obtained. Choice C is incorrect as it overestimates the relative error. Choice D is incorrect as it underestimates the relative error.

Correct Answer: C

Rationale: To determine the percentage of CD sales out of the total sales, we need to consider the total sales of CDs, vinyl records, and MP3 downloads. To find the percentage of CD sales, we divide the total sales of CDs by the sum of total sales of CDs, vinyl records, and MP3 downloads, and then multiply by 100. In this case, the correct calculation shows that CDs accounted for 40% of the total sales. Choice A (55%) is incorrect as it overestimates the contribution of CDs. Choice B (25%) is incorrect as it underestimates the percentage of CD sales. Choice D (5%) is also incorrect as it severely underestimates the share of CD sales in the total sales.