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

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?

A. 100ml 10% solution, 100ml water
B. 150ml 10% solution, 50ml water
C. 160ml 10% solution, 40ml water
D. 200ml 10% solution, 0ml water

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. If 3 nurses can care for 15 patients, how many nurses are needed for 25 patients?

A. 4
B. 5
C. 6
D. 7

Correct answer: B

Rationale: To determine how many nurses are needed for 25 patients, set up a proportion: 3 nurses / 15 patients = x nurses / 25 patients. Cross multiply to solve for x: 3 * 25 = 15 * x. This simplifies to 75 = 15x. Divide both sides by 15 to find x = 5. Therefore, 5 nurses are needed for 25 patients. Choices A, C, and D are incorrect as they do not correspond to the correct calculation based on the given proportion.

3. What is the average of the numbers 14, 73, and 7?

A. 28.57
B. 30.57
C. 29.56
D. 31.33

Correct answer: D

Rationale: The correct answer is D. Adding 14 + 73 + 7 gives a total of 94. To find the average, we divide the sum by the number of values (3), which equals 31.33. Rounding this average to two decimal places gives us 31.33, which corresponds to option D. Choices A, B, and C are incorrect as they do not correctly calculate the average of the given numbers. Choice A is close to the sum of the numbers, not the average. Choices B and C are also not correct averages calculated from the provided numbers.

4. If 30% of a given number is 18, what is the full number?

A. 60
B. 30
C. 40
D. 45

Correct answer: A

Rationale: If 30% of a number is 18, you can find the full number by dividing 18 by 0.30 (the decimal equivalent of 30%). This calculation results in 60. Therefore, the full number is 60. Choice B (30) is the result if 30% of the number itself was calculated, not the full number. Choices C (40) and D (45) are incorrect and do not align with the given information.

5. Express the ratio of 12:15 as a percentage.

A. 58.80%
B. 62%
C. 75.25%
D. 80%

Correct answer: C

Rationale: To express the ratio 12:15 as a percentage, you need to find the total parts in the ratio (12 + 15 = 27), then divide one part by the total (12 ÷ 27 = 0.4444). Finally, convert the decimal to a percentage by multiplying by 100 (0.4444 x 100 = 44.44%). Therefore, the ratio 12:15 is equivalent to 44.44% when rounded to two decimal places, which is closest to 75.25% among the answer choices. Choices A, B, and D are incorrect as they do not represent the correct percentage equivalent of the ratio 12:15.