HESI A2
HESI A2 Quizlet Math
1. 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.
2. Change the following percentage to a decimal: 0.03%
- A. 0.03
- B. 0.0003
- C. 0.3
- D. 0.003
Correct answer: B
Rationale: To convert a percentage to a decimal, divide by 100. Therefore, 0.03% ÷ 100 = 0.0003. The correct answer is B. Choice A (0.03) is incorrect because it does not account for the conversion of percentage to decimal. Choice C (0.3) is incorrect as it represents 0.03 as 30% rather than 0.03%. Choice D (0.003) is also incorrect as it does not accurately convert 0.03% to a decimal.
3. You need to repaint a cylindrical water tank with a diameter of 2 meters and a height of 3 meters. Assuming one can of paint covers 10 sq m, how many cans do you need to cover only the exterior surface?
- A. 6 cans
- B. 9 cans
- C. 12 cans
- D. 15 cans
Correct answer: C
Rationale: To find the surface area of the cylinder, calculate the lateral surface area using the formula 2πrh, where r is the radius (half of the diameter) and h is the height. Substituting the values, we get 2 * π * 1 * 3 = 6π square meters. Since each can covers 10 sq m, divide the total surface area by the coverage area per can: 6π / 10 ≈ 1.9 cans. Since you can't buy a fraction of a can, you would need to round up, so you would need 2 cans to cover the entire exterior surface. Therefore, you would need 2 * 6 = 12 cans in total. Choices A, B, and D are incorrect as they do not consider the correct surface area calculation or the rounding up to the nearest whole number of cans required.
4. A roast was cooked at 325°F in the oven for 4 hours. The internal temperature rose from 32°F to 145°F. What was the average rise in temperature per hour?
- A. 20
- B. 32
- C. 28
- D. 37°F/hr
Correct answer: C
Rationale: The temperature increased from 32°F to 145°F, resulting in a total increase of 145°F - 32°F = 113°F. Dividing this total increase by the 4 hours of cooking time gives an average rise of 113°F ÷ 4 = 28.25°F per hour, which can be rounded to 28°F per hour. Therefore, the correct answer is 28. Choice A (20) is incorrect because it does not reflect the actual average rise in temperature per hour. Choice B (32) is incorrect as it does not consider the total temperature increase and divide it by the total hours. Choice D (37°F/hr) is incorrect as it does not match the calculated average rise in temperature per hour.
5. Fred's rule for computing an infant's dose of medication is: infant's dose = (Child's age in months x adult dose) / 150. If the adult dose of medication is 15 mg, how much should be given to a 2-year-old child?
- A. 2.4 mg
- B. 3
- C. 48 mg
- D. 1
Correct answer: A
Rationale: To calculate the dose for a 2-year-old child using Fred's rule, we substitute the child's age (24 months) and the adult dose (15 mg) into the formula: (24 x 15) / 150 = 2.4 mg. Therefore, the correct answer is A, representing 2.4 mg for a 2-year-old child. Choice B is incorrect as it does not match the calculated dose. Choice C is incorrect as it does not consider the formula provided. Choice D is incorrect as it does not reflect the correct calculation based on the given information.
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