Jessica buys 10 cans of paint. Red paint costs $1 per can, and blue paint costs $2 per can. In total, she spends $16. How many red cans did she buy?

Correct Answer: C

Rationale: Let r be the number of red cans and b be the number of blue cans. The total cans equation is r + b = 10. The total cost equation is r + 2b = 16. By solving these equations simultaneously, we find r = 4. Therefore, Jessica bought 4 red cans. Choice A, 2 red cans, is incorrect because it does not satisfy the total cans or total cost condition. Choices B and D are also incorrect as they do not fulfill both conditions simultaneously.

Correct Answer: D

Rationale: To convert a decimal to a percent, you multiply by 100. Therefore, 0.80 * 100 = 80%. The correct answer is D. Choice A (40%) is incorrect as 0.80 is not equivalent to 40%. Choice B (125%) is incorrect as it is greater than 100%. Choice C (90%) is incorrect as it does not reflect the correct conversion of 0.80 to a percent.

Correct Answer: A

Rationale: To find the sum of fractions, add the numerators if the denominators are the same. Here, 3/8 + 5/8 = (3+5)/8 = 8/8 = 1. Therefore, the correct answer is A. Choices B, C, and D are incorrect because they do not represent the correct sum of the fractions provided in the question.

Correct Answer: A

Rationale: To round 8.067 to the nearest tenth, you look at the digit in the hundredth place, which is 6. Since 6 is equal to or greater than 5, you round up the digit in the tenth place. Therefore, 8.067 rounded to the nearest tenth is 8.1. Choice B (8.1) is incorrect as it duplicates the correct answer. Choice C (8) is incorrect as it does not account for the decimal part. Choice D (8.11) is incorrect as it rounds the number to the nearest hundredth, not the nearest tenth.

Correct Answer: B

Rationale: The correct answer is B: N/40. To find 40% of N, you multiply N by 0.4, so 0.4N is the correct representation. Choice B, N/40, is incorrect because dividing N by 40 does not give you 40% of N. Choice C, 2/5 N, is equivalent to 40% of N since 2/5 is the same as 40% when simplified. Choice D, 40N/100, is also correct since 40% can be represented as 40/100, which simplifies to 0.4, making 40N/100 another valid way to write 40% of N.

Correct Answer: C

Rationale: Let r be the number of red cans and b be the number of blue cans. The total cans equation is r + b = 10. The total cost equation is r + 2b = 16. By solving these equations simultaneously, we find r = 4. Therefore, Jessica bought 4 red cans. Choice A, 2 red cans, is incorrect because it does not satisfy the total cans or total cost condition. Choices B and D are also incorrect as they do not fulfill both conditions simultaneously.

Correct Answer: B

Rationale: To find the area of a rectangle, you multiply its length by its width. In this case, the length is 5 cm and the width is 4 cm. So, Area = length * width = 5 cm * 4 cm = 20 cm². Therefore, the correct answer is 20 cm². Choice A (9 cm²), Choice C (10 cm²), and Choice D (25 cm²) are incorrect as they do not result from the correct calculation of multiplying the length and width of the rectangle.

Correct Answer: C

Rationale: To find the sum of all six numbers, we multiply the average (6) by the total numbers (6), which equals 36. Since the sum of five numbers is 25, the sixth number can be found by subtracting the sum of five numbers from the total sum: 36 - 25 = 11. Therefore, the sixth number is 11. Choice A, 8, is incorrect because adding 8 to the sum of five numbers (25) would result in a total greater than the correct sum of all six numbers (36). Choice B, 10, is incorrect because adding 10 to the sum of five numbers (25) would also result in a total greater than the correct sum of all six numbers (36). Choice D, 12, is incorrect because adding 12 to the sum of five numbers (25) would exceed the correct sum of all six numbers (36).

Correct Answer: D

Rationale: The factors of 12 are numbers that divide evenly into 12 without leaving a remainder. The correct factors of 12 are 1, 2, 3, 4, 6, and 12. Choice A (12, 24, 36) is incorrect as only 12 is a factor of 12. Choice B (1, 2, 4, 6, 12) includes all the correct factors of 12. Choice C (12, 24, 36, 48) is incorrect as 24, 36, and 48 are not factors of 12.