Correct Answer: D

Rationale: To convert a fraction to a percentage, you multiply the fraction by 100. In this case, 3/4 * 100% = 75%. Therefore, the correct answer is D. Choice A (57%) is incorrect as it does not represent the fraction 3/4. Choice B (7.50%) is incorrect as it is not the equivalent percentage of 3/4. Choice C (65%) is incorrect as it does not match the percentage value of 3/4.

Correct Answer: A

Rationale: The correct expression for the sum of three times a number and eight times a different number is given by 3x + 8y. This represents adding three times the variable x (3x) to eight times the variable y (8y). Choice B (8x + 3x) is incorrect as it represents adding eight times x to three times x, which is redundant. Choice C (3x - 8y) is incorrect because it represents subtracting eight times y from three times x, not their sum. Choice D (8x - 3y) is also incorrect as it represents subtracting three times y from eight times x, not their sum.

Correct Answer: A

Rationale: The correct answer is A: 'Itself.' When any number is raised to the power of 1, it remains unchanged and is equal to itself. This is a fundamental property of exponents. Choice B, 'One,' is incorrect because raising a number to the power of 1 does not result in the answer being 1. Choice C, 'Zero,' is incorrect as any non-zero number raised to the power of 1 is itself, not zero. Choice D, 'The number multiplied by 2,' is incorrect because raising a number to the power of 1 does not involve multiplying it by 2.

Correct Answer: A

Rationale: A proper fraction is characterized by having a numerator smaller than the denominator, while an improper fraction has a numerator larger than the denominator. Therefore, choice A is correct. Choice B is incorrect because it states the opposite relationship between the numerator and denominator for proper and improper fractions. Choice C is incorrect as it describes a fraction where the numerator is equal to the denominator, which is a different concept. Choice D is incorrect as it associates a numerator being smaller than the denominator with an improper fraction, which is inaccurate.

Correct Answer: A

Rationale: Choice A represents no correlation between two variables as it states that as a student's class attendance decreases, the student's overall grade remains the same. This scenario shows no relationship between class attendance and grade. In contrast, choices B, C, and D show clear correlations between the variables mentioned. Choice B indicates a negative correlation between exercise hours and weight gain, choice C indicates a negative correlation between miles driven and gasoline in the tank, and choice D indicates a positive correlation between water intake and plant growth rate, making them all examples of correlated relationships.