What is the total surface area of a lampshade consisting of a cylindrical base (diameter 20cm, height 10cm) and a hemispherical top (same diameter as the base)?

Correct Answer: D

Rationale: To find the total surface area of the lampshade, first calculate the surface area of the cylinder and the hemisphere separately. 1. Surface area of the cylinder = 2πr² + 2πrh = 2π(10)² + 2π(10)(20) = 400π + 400π = 800π cm². 2. Surface area of the hemisphere = 2πr² (since it's a half sphere) = 2π(10)² = 200π cm². Adding both areas gives the total surface area: 800π + 200π = 1000π cm². Now, calculate the numerical value: 1000π ≈ 3141.59 cm², which is approximately equal to 2055 cm². Therefore, the correct answer is 2055 sq cm. Choice A (785 sq cm) is incorrect as it is much smaller than the correct answer. Choices B (1130 sq cm) and C (1570 sq cm) are also incorrect as they do not account for the total surface area of the lampshade.

Correct Answer: B

Rationale: To convert 98.6 degrees Fahrenheit to Celsius, you can use the formula (98.6 - 32) 5/9. By solving this equation, the temperature is calculated to be 37°C. Therefore, the correct answer is B, 37 Celsius. Choice A, 35 Celsius, is incorrect because it is not the outcome of the conversion formula. Choice C, 38 Celsius, is incorrect as well, as it does not match the correct conversion result. Choice D, 36.5 Celsius, is also incorrect as it does not correspond to the accurate conversion from 98.6 degrees Fahrenheit.

Correct Answer: A

Rationale: To multiply fractions, multiply the numerators together and the denominators together. In this case, 3/4 1/3 = (3 1) / (4 3) = 3/12 = 1/4. Therefore, the correct answer is A: 1/4. Choices B (1/3), C (3/5), and D (3/8) are incorrect because they do not result from the correct multiplication of the given fractions.

Correct Answer: D

Rationale: To find the result of subtracting 8.4 from 3.7, you need to subtract 3.7 from 8.4. Performing this subtraction, 8.4 - 3.7 equals 4.7. Therefore, the correct answer is 4.7. Choice A, 4.5, is incorrect as it is not the result of subtracting 8.4 from 3.7. Choices B and C, 4.8 and 4.6 respectively, are also incorrect as they do not match the correct subtraction result of 4.7.

Correct Answer: B

Rationale: To convert grams to kilograms, you need to divide by 1000 since there are 1000 grams in a kilogram. Therefore, 2000 grams is equal to 2 kilograms (2000 grams · 1000 = 2 kilograms). The correct answer is B: 2 kilograms. Choice A, 20 kilograms, is incorrect because multiplying by 10 (not dividing by 1000) would give that result. Choice C, 5 kilograms, and Choice D, 10 kilograms, are also incorrect as they do not correctly convert grams to kilograms.

Correct Answer: B

Rationale: To find the total number of shipping labels needed, multiply the number of boxes by the labels per box: 9 boxes * 3 labels per box = 27 labels. Therefore, the worker needs 27 shipping labels each day. Choice A, 24 labels, is incorrect because it results from multiplying 9 boxes by 3 labels without calculating the correct total. Choice C, 20 labels, is incorrect as it underestimates the total number of labels needed. Choice D, 30 labels, is incorrect as it overestimates the total by multiplying incorrectly.

Correct Answer: A

Rationale: A six-sided die has three odd numbers (1, 3, 5) out of six possible outcomes. To calculate the probability, divide the number of favorable outcomes (odd numbers) by the total number of outcomes: 3/6 = 0.5 or 50%. Therefore, the probability of rolling an odd number on a six-sided die is 50%. Choice A is correct. Choice B (66.70%) is incorrect as it does not represent the correct probability of rolling an odd number on a six-sided die. Choice C (33.30%) is incorrect as it represents the probability of rolling an even number. Choice D (25%) is incorrect as it does not reflect the correct probability of rolling an odd number on a six-sided die.

Correct Answer: A

Rationale: To determine the distance traveled by the train, you multiply the speed by the time: 60 mph 2 hours = 120 miles. Therefore, the correct answer is 120 miles. Choice B, 180 miles, is incorrect as it results from multiplying the speed by 3 hours instead of 2. Choice C, 100 miles, is incorrect as it results from multiplying the speed by 1.5 hours. Choice D, 240 miles, is incorrect as it results from multiplying the speed by 4 hours instead of 2.

Correct Answer: A

Rationale: The probability of rolling a specific number on a six-sided die is calculated by dividing the favorable outcomes (rolling a 3) by the total possible outcomes. In this case, there is 1 favorable outcome (rolling a 3) out of 6 total possible outcomes (numbers 1 to 6 on the die). Therefore, the probability of rolling a 3 is 1/6. Choice B (1/4), C (1/3), and D (1/2) are incorrect because they do not represent the correct calculation of the probability for rolling a 3 on a six-sided die.