Correct Answer: B

Rationale: To determine the percentage of income remaining after spending 15%, subtract the percentage spent from 100% (100% - 15% = 85%). Therefore, Mary has 85% of her income left, which aligns with answer choice B. Choice A (12%) is incorrect because it represents the remaining amount after spending 88% of her income. Choice C (75%) is incorrect as it does not account for the 15% already spent. Choice D (95%) is incorrect as it does not consider the amount spent by Mary.

Correct Answer: D

Rationale: To find the amount of medication delivered in one hour, we first calculate the amount delivered in one minute by multiplying the number of drops per minute (40) by the volume of each drop (0.05 milliliters). This gives us 2 milliliters per minute. Then, to find the total amount delivered in one hour, we multiply 2 milliliters per minute by the number of minutes in an hour (60), resulting in 120 milliliters. Therefore, the correct answer is 120 milliliters. Choices A, B, and C are incorrect as they do not correctly calculate the total volume of medication delivered in one hour.

Correct Answer: D

Rationale: To find the total surface area, we need to calculate the surface area of the cylindrical body and both hemispherical ends separately. The surface area of the cylinder is the sum of the lateral surface area (2πrh) and the area of the two circular bases (2πr^2). For the hemispheres, the surface area of one hemisphere is (2πr^2), so for two hemispheres, it would be (4πr^2). Given that the diameter of the cylinder and hemispherical ends is 10cm, the radius (r) is 5cm. Calculating the individual surface areas: Cylinder = 2π(5)(20) + 2π(5)^2 = 200π + 50π = 250π. Hemispheres = 4π(5)^2 = 100π. Adding these together gives a total surface area of 250π + 100π = 350π cm^2, which is approximately equal to 2055 sq cm. Therefore, the correct answer is D. Choice A (785 sq cm) is incorrect as it is significantly lower than the correct calculation. Choices B (1130 sq cm) and C (1570 sq cm) are also incorrect as they do not reflect the accurate surface area calculation for the given dimensions.

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: D

Rationale: The difference between the original price ($200) and the new price ($150) is $50. To find the percentage decrease, divide the difference by the original price and multiply by 100: ($50 / $200) 100 = 25%. Therefore, the correct answer is D, meaning the price decreased by 25%. Choices A, B, and C are incorrect as they do not accurately represent the percentage decrease in price.