Correct Answer: B

Rationale: To find X in the given proportion 81:X::9:27, you can set up the equation 81/X = 9/27. Cross-multiplying gives 81 * 27 = 9 * X, which simplifies to 2187 = 9X. Dividing both sides by 9 results in X = 27. Therefore, the correct answer is B. Choice A (3) is incorrect as it does not satisfy the proportion. Choice C (21) is incorrect as it is not the correct value to make the proportion valid. Choice D (9) is incorrect as it does not align with the proportion provided.

Correct Answer: A

Rationale: The correct answer is A, $33.59. To find out how much money she would have left, we need to calculate the total spending by adding the amounts spent at the groceries, dry cleaners, and pet store: $101.85 + $21.90 + $42.66 = $166.41. Subtract the total spending from the initial cash amount to determine the remaining cash: $200.00 - $166.41 = $33.59. Choice B, $29.59, is incorrect as it does not accurately reflect the correct calculation. Choices C and D, $25.59 and $21.59 respectively, are also incorrect as they do not consider the correct total spending amount and subtraction from the initial cash.

Correct Answer: D

Rationale: To convert meters to kilometers, divide the number of meters by 1000, as 1 kilometer is equal to 1000 meters. Therefore, 200 meters is equivalent to 200 / 1000 = 0.2 kilometers. Choices A, B, and C are incorrect because they do not correctly convert meters to kilometers. A provides an answer that would be correct if converting from kilometers to meters. B and C are much larger distances than what 200 meters represent.

Correct Answer: A

Rationale: Let the width of the rectangle be x cm, and its length be 2x cm. The area of the rectangle is 2x * x = 2x², and the area of the square is 12² = 144 cm². Setting the areas equal gives 2x² = 144. Solving for x gives x = 6. Thus, the width is 6 cm, and the length is 12 cm. The perimeter is 2(6 + 12) = 36 cm. Therefore, the correct answer is 36 cm. Choice B, 46 cm, is incorrect because it does not match the calculated perimeter. Choices C and D are also incorrect as they do not reflect the correct calculation of the rectangle's perimeter.

Correct Answer: A

Rationale: The correct ratio of men to women is 3:4. To find the ratio, divide the number of men by the number of women: 12 men / 16 women = 3/4, which simplifies to 3:4. Therefore, in a class of 28 people with 12 men and 16 women, the ratio of men to women is 3:4. Choice B (4:7) is incorrect because it does not accurately reflect the given numbers of men and women in the class. Choice C (12:16) is incorrect as it represents the actual count of men and women, not the ratio. Choice D (1:2) is incorrect as it does not match the proportion of men to women in the class.