Correct Answer: D

Rationale: To calculate a 30% increase from the current dosage of 270 mg, first find 30% of 270, which is 81 mg. Add this 81 mg increase to the original dosage of 270 mg to get the new dosage, which is 351 mg (270 mg + 81 mg = 351 mg). Therefore, the correct answer is 351 mg. Choice A (81 mg) is incorrect because this value represents only the calculated 30% increase, not the total dosage after the increase. Choice B (270 mg) is the original dosage and does not account for the 30% increase. Choice C (300 mg) is close to the correct answer but does not consider the precise 30% increase calculation, leading to an incorrect total dosage.

Correct Answer: C

Rationale: The correct answer is C: 'As elevation increases, temperature decreases.' In a negative correlation, the variables move in opposite directions. As elevation rises, temperature tends to decrease. Choice A is incorrect because a negative correlation implies that as one variable increases, the other decreases. Choices B and D are incorrect because they suggest that temperature either remains the same or increases as elevation decreases or increases, which is inconsistent with a negative correlation.

Correct Answer: C

Rationale: To find the amount the friend paid, you can set up the equation 2x - 2000 = 48000, where x represents the amount the friend paid. Solving this equation gives x = $25,000. Therefore, the friend paid $25,000. Choice A ($23,000) is incorrect because it does not account for the $2,000 difference mentioned in the question. Choice B ($46,000) is incorrect because it is double the amount needed. Choice D ($50,000) is incorrect as it does not consider the $2,000 less mentioned in the question.

Correct Answer: A

Rationale: A quotient is the result of dividing one number by another. Choice A is correct because it accurately defines a quotient as the outcome of a division operation. Choice B is incorrect because it describes the result of multiplying two numbers, not dividing them. Choice C is incorrect because it refers to the remainder of a subtraction operation, not a division. Choice D is incorrect because it mentions the number remaining after a division, which is typically referred to as the remainder and not the quotient.

Correct Answer: A

Rationale: An equivalent fraction is a fraction that may look different in terms of its numerator and denominator but still represents the same value or quantity. This means that when you simplify or expand a fraction, its value remains unchanged. Choice B and C are incorrect because equivalent fractions are not determined by being smaller or larger than another fraction; it is about representing the same quantity. Choice D is incorrect because equivalent fractions may have different numerators as long as the ratio between the numerator and denominator remains the same.