Correct Answer: A

Rationale: An exponent is a number that indicates how many times a base number is multiplied by itself. The correct answer (A) accurately defines an exponent as a multiplier that shows how many times a number should be multiplied by itself. Choice B is incorrect as it describes a factor rather than an exponent. Choice C is incorrect as it defines a divisor, not an exponent. Choice D is incorrect as it specifically refers to the square of a number, which is not a general definition of an exponent.

Correct Answer: B

Rationale: To find the average time per mile, add the total time taken to cover all miles and then divide by the total miles run. The athlete ran 5 miles in 25 minutes and 3 miles in 15 minutes, totaling 8 miles in 40 minutes. Therefore, the average time per mile is 40 minutes · 8 miles = 5 minutes. Choice A, 7 minutes, is incorrect as it does not reflect the correct average time per mile. Choice C, 6.5 minutes, is incorrect since the calculation is not based on the given information. Choice D, 8.5 minutes, is incorrect as it does not represent the average time per mile for the entire run.

Correct Answer: A

Rationale: The correct answer is A. Using the Pythagorean theorem (A² + B² = C²), we substitute the values: 5² + 12² = 13². This simplifies to 25 + 144 = 169, which is true. Therefore, 5 inches and 12 inches could be the lengths of the other two sides. Choices B, C, and D do not satisfy the Pythagorean theorem, making them incorrect options.

Correct Answer: A

Rationale: To solve 3.45 * 0.53, multiply the numbers to get 1.8285. Therefore, the correct answer is A. Choice B is incorrect because it incorrectly moves the decimal point. Choice C is incorrect as it is a fraction of the correct answer. Choice D is incorrect as it results from an error in moving the decimal point.

Correct Answer: C

Rationale: To convert liters to milliliters, you need to know that 1 liter is equal to 1000 milliliters. Therefore, 3.2 liters is equivalent to 3.2 x 1000 = 3200 milliliters. Choice A (0.32) is incorrect as it incorrectly moves the decimal point. Choice B (32) is incorrect as it doesn't consider the conversion factor between liters and milliliters. Choice D (320) is incorrect as it is a partial conversion error, missing a zero at the end.