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The price dropped from $200 to $150. By what percentage did the price decrease?
- A. 5%
- B. 10%
- C. 20%
- D. 25%
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.
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A pressure vessel has a cylindrical body (diameter 10cm, height 20cm) with hemispherical ends (same diameter as the cylinder). What is its total surface area?
- A. 785 sq cm
- B. 1130 sq cm
- C. 1570 sq cm
- D. 2055 sq cm
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.
How many liters are in 5000 milliliters?
- A. 5 liters
- B. 4 liters
- C. 6 liters
- D. 5.5 liters
Correct Answer: A
Rationale: To convert milliliters to liters, you divide by 1000 since 1000 milliliters make up 1 liter. In this case, 5000 milliliters divided by 1000 milliliters per liter equals 5 liters (5000 mL · 1000 mL/L = 5 L). Therefore, the correct answer is A: 5 liters. Choice B, 4 liters, is incorrect because 5000 milliliters is equivalent to 5 liters, not 4. Choice C, 6 liters, is incorrect as it is not the accurate conversion from milliliters to liters in this case. Choice D, 5.5 liters, is incorrect as it does not reflect the correct conversion of 5000 milliliters to liters, which is 5 liters.
If 3 books cost $4, how much will 6 books cost?
- A. $8
- B. $12
- C. $6
- D. $10
Correct Answer: A
Rationale: To find the cost of 1 book, divide the total cost by the number of books: $4 / 3 = $1.33 per book. To determine the cost of 6 books, multiply the cost per book by 6: $1.33 * 6 = $8. Therefore, purchasing 6 books will cost $8. Choice B, $12, is incorrect as it incorrectly doubles the cost of 3 books. Choice C, $6, is incorrect as it is half the cost of 3 books. Choice D, $10, is incorrect as it does not accurately calculate the cost of 6 books based on the given information.
How many meters are in 3 kilometers?
- A. 3000 meters
- B. 2000 meters
- C. 3500 meters
- D. 2500 meters
Correct Answer: A
Rationale: The correct answer is A: 3000 meters. To convert kilometers to meters, you need to know that there are 1000 meters in 1 kilometer. Therefore, to find the number of meters in 3 kilometers, you multiply 3 by 1000, resulting in 3000 meters. Choice B, 2000 meters, is incorrect as it doesn't account for the correct conversion factor. Choice C, 3500 meters, and Choice D, 2500 meters, are also incorrect as they provide inaccurate conversions.
81:X::9:27. Find X.
- A. 3
- B. 27
- C. 21
- D. 9
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.