a lab needs 200ml of a 5 salt solution they only have a 10 solution how much 10 solution and water should be mixed
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HESI A2

HESI A2 Math Portion

1. A lab needs 200ml of a 5% salt solution. They only have a 10% solution. How much 10% solution and water should be mixed?

Correct answer: B

Rationale: Rationale: 1. Let x be the volume of the 10% solution needed and y be the volume of water needed. 2. The total volume of the final solution is 200ml, so x + y = 200. 3. The concentration of the final solution is 5%, so the amount of salt in the final solution is 0.05 * 200 = 10g. 4. The amount of salt in the 10% solution is 0.1x, and the amount of salt in the water is 0, so the total amount of salt in the final solution is 0.1x. 5. Since the total amount of salt in the final solution is 10g, we have 0.1x = 10. 6. Solving for x, we get x = 100ml. 7. Substituting x =

2. A decorative globe has a diameter of 25cm. What is its total surface area?

Correct answer: B

Rationale: To find the total surface area of a sphere, you can use the formula: 4 * π * (radius)^2, where the radius is half the diameter. Given that the diameter is 25cm, the radius is half of that, which is 12.5cm. Substitute this value into the formula: 4 * π * (12.5cm)^2 ≈ 1963 sq cm. Therefore, the total surface area of the decorative globe is approximately 1963 sq cm. Choices A, C, and D are incorrect as they do not correspond to the correct calculation.

3. If Andy runs five times as long as Jake, and Jake runs 24.5 miles each week, how many miles does Andy run in a day?

Correct answer: A

Rationale: To find how many miles Andy runs in a day, we need to calculate the distance Andy runs in a week. Since Andy runs five times as long as Jake, Andy runs 5 * 24.5 = 122.5 miles per week. To convert this to miles per day, we divide by 7 (days in a week): 122.5 / 7 = 17.5 miles per day. Therefore, the correct answer is A. Choices B, C, and D are incorrect as they do not accurately reflect the calculation based on the given ratio.

4. A person is laying stones for a garden. They have 1,200 stones. Each stone covers an area of 0.75 square feet. What is the total area that the stones will cover?

Correct answer: A

Rationale: To find the total area covered by the stones, multiply the number of stones by the area each stone covers: 1,200 stones * 0.75 sq ft = 900 sq ft. Therefore, the stones will cover 900 sq ft, which is closest to 800 sq ft among the answer choices A, B, C, and D. The correct answer is A, 800 sq ft. Choices B, C, and D are incorrect as they do not result from the correct calculation of multiplying the number of stones by the area each stone covers.

5. A hospital day staff consists of 25 registered nurses, 75 unlicensed assistants, five phlebotomists, six receptionists and office staff, and 45 physicians. One summer day the staff was at only 68% strength. How many people were working that day?

Correct answer: A

Rationale: To find the total number of staff members, sum up the different roles: 25 (nurses) + 75 (assistants) + 5 (phlebotomists) + 6 (office staff) + 45 (physicians) = 156 total staff. Then, calculate 68% of the total staff: 156 × 0.68 = 106.08, which is approximately 106 people. Therefore, 106 people were working that day. Choice A is correct. Choices B, C, and D are incorrect as they do not reflect the accurate calculation based on the given information.

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