Correct Answer: D

Rationale: If 20 students are divided into pairs, there would be 10 pairs in total (20 students / 2 = 10 pairs). Since each pair receives 10 pencils, the total number of pencils needed is calculated by multiplying the number of pairs (10 pairs) by the number of pencils each pair receives (10 pencils per pair), resulting in 100 pencils required. Therefore, the correct answer is 100 pencils. Choices A, B, and C are incorrect because they do not consider the correct pairing of students or the total number of pencils needed for each pair.

Correct Answer: B

Rationale: To calculate how much Donald earns from selling a house for $152,000 at an 8% commission rate, we multiply the selling price by the commission rate: $152,000 x 0.08 = $12,160. Therefore, he earns $12,160. Choice A, $12,160, is the correct answer as calculated. Choices C and D are incorrect amounts as they do not result from the given information. Choice C, $19,000, is significantly higher than the correct calculation, and choice D, $21,600, is the result of incorrectly adding the commission to the selling price instead of calculating the commission earned.

Correct Answer: C

Rationale: Let Lulu's sister's age be x. According to the given information, x = 15 (cousin's age) + 7 = 22. So, Lulu's sister is 22 years old. Since Lulu is 5 years younger than her sister, Lulu's age is 22 - 5 = 17. Therefore, Lulu is 17 years old. Choices A, B, and D are incorrect because they do not correspond to the calculations based on the information provided in the question.

Correct Answer: A

Rationale: If she puts aside 1/3 of her paycheck for rent and utilities, this means she spends 3 portions in total. So, 1 portion represents 1/3 of the paycheck. Since she spends $75 on groceries, it leaves 2 portions. The total amount of 3 portions is the paycheck. To find out one portion, divide the total paycheck by 3: Paycheck = 3 portions. $75 is one portion. Multiply the one portion by 3 to find the total paycheck: $75 * 3 = $225. Subtract the spent amount from the weekly paycheck: $225 - $75 = $150. Therefore, the amount left from her weekly paycheck is $150. The other choices are incorrect because they do not follow the correct calculation based on the given information.

Correct Answer: B

Rationale: To multiply 52 by 04, you first multiply the two numbers together: 52 x 4 = 208. Since there are two decimal places in the expression, you need to divide the result by 100, which gives you 0.0208. Therefore, the correct answer is B. Choice A (0.00208) is incorrect because it represents a much smaller value obtained by considering the decimal incorrectly. Choice C (0.208) is incorrect because it does not account for the decimal placement. Choice D (2.08) is incorrect as it does not consider the requirement to convert the result into decimal form.