if larry can wash 50 cars in 20 minutes how many minutes will it take him to wash 80 cars

HESI A2

HESI A2 Math

1. If Larry can wash 50 cars in 20 minutes, how many minutes will it take him to wash 80 cars?

A. 20 minutes
B. 32 minutes
C. 40 minutes
D. 60 minutes

Correct answer: B

Rationale: To determine how many minutes it will take Larry to wash 80 cars, we first calculate his rate of washing cars per minute: 50 cars / 20 minutes = 2.5 cars per minute. To wash 80 cars, we divide the total number of cars by the cars washed per minute: 80 cars / 2.5 cars per minute = 32 minutes. Hence, it will take Larry 32 minutes to wash 80 cars. Choices A, C, and D are incorrect as they do not align with the correct calculation based on Larry's rate of washing cars.

2. You need to buy cardboard to cover a rectangular box with dimensions 40cm by 30cm by 25cm. Considering only the exterior surfaces (not flaps or openings), how much cardboard do you need (assume one sheet covers 0.5 sq m)?

A. 0.3 sq m
B. 0.6 sq m
C. 1.2 sq m
D. 1.8 sq m

Correct answer: C

Rationale: To find the total surface area of the rectangular box, calculate the area of each side and sum them up. The areas of the sides are: 2(40x30) + 2(40x25) + 2(30x25) = 2400 + 2000 + 1500 = 5900 sq cm. Convert this to square meters by dividing by 10,000: 5900/10,000 = 0.59 sq m. Since one sheet covers 0.5 sq m, you would need 2 sheets to cover the box fully, which equals 1 sq m. Therefore, the correct answer is 1.2 sq m. Choice A (0.3 sq m) is too small for the dimensions provided. Choice B (0.6 sq m) is incorrect as it doesn't match the calculated surface area. Choice D (1.8 sq m) is too high for the surface area of the box.

3. Round to the nearest whole number. Change the fraction to a percent: 17/80 =

A. 20%
B. 21%
C. 22%
D. 23%

Correct answer: B

Rationale: To convert 17/80 to a percent, we divide 17 by 80 to get 0.2125. Multiplying by 100, we get 21.25%. Rounding to the nearest whole number, 21.25% becomes 21%. Choice A (20%) is incorrect because rounding 21.25% down to the nearest whole number gives 21%. Choice C (22%) is incorrect as it is the next whole number after 21. Choice D (23%) is incorrect as it is more than 21.25% and thus rounds up to 22%.

4. Subtract 12 - 7 4\5.

A. 5 1\5
B. 5 2\5
C. 4 5\6
D. 3 1\3

Correct answer: A

Rationale: Subtract the whole numbers and then subtract the fractions: 12 - 7 4\5 = 5 1\5.

5. How many gallons are in 576 fluid ounces?

A. 4 gallons
B. 5 gallons
C. 6 gallons
D. 3 gallons

Correct answer: A

Rationale: To convert fluid ounces to gallons, you need to know that there are 128 fluid ounces in a gallon. To find how many gallons are in 576 fluid ounces, divide 576 by 128, which equals 4.5 gallons. Since we are looking for the closest whole number, the answer is 4 gallons. Choice A is correct. Choice B, C, and D are incorrect as they do not accurately represent the conversion from fluid ounces to gallons.