Correct Answer: B

Rationale:
To find the sum of numbers from 1 to 6, we add them together: 1 + 2 + 3 + 4 + 5 + 6 = 21.
Therefore, the correct answer is 21.
Choice A (30) is incorrect because it is not the sum of the numbers 1 to 6.
Choice C (15) is incorrect as it is the sum of numbers 1 to 5.
Choice D (13) is incorrect as it is the sum of numbers 1 to 4, not 1 to 6.

Correct Answer: A

Rationale:
To convert miles to kilometers, the conversion factor is 1 mile ≈ 1.609 kilometers.
Therefore, to convert 67 miles to kilometers, you would multiply: 67 miles 1.609 km/mile = 107.703 km. When rounded to three significant digits, this gives 108 km.
Therefore, 67 miles is approximately 108 kilometers.
Choice A is correct because it is the closest rounded value to three significant digits.

Choices B, C, and D are incorrect as they do not match the calculated conversion of 108 km.

Correct Answer: A

Rationale: The student's score is calculated by adding the points earned for correct answers (x) and subtracting the points lost for incorrect answers (y/2).
Therefore, the expression for the student's score on the exam is x - y/2. Option A is correct because it accurately represents this calculation. Option B (x - y) is incorrect as it does not account for the penalty of losing half a point for each incorrect answer. Option C (30 - (x + y)) is incorrect as it subtracts the total number of questions from the sum of correct and blank answers, which does not represent the scoring system. Option D (30 - x - y/2) is also incorrect as it incorrectly subtracts x from 30 and then deducts y divided by 2, which is not the correct scoring method for the exam.

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 find out how many days Bernard needs to work to make $300, we divide the total amount he needs by how much he makes per day: $300 / $80 = 3.75 days. Since Bernard can only work full days, he would need to work for 4 days to make $300.
Therefore, the correct answer is 4 days.
Choice A (2 days) is incorrect because it does not match the calculation based on his daily earnings.
Choice B (3 days) is incorrect as the calculated result is not a whole number, so Bernard needs to work for more than 3 days.
Choice D (5 days) is incorrect as it exceeds the calculated number of days needed to make $300.