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. Subtract 32 divided by 8\9.

A. 36
B. 32
C. 40
D. 44

Correct answer: A

Rationale: 32 ÷ (8\9) is the same as 32 × (9\8) = 36.

3. What is the ratio of women to the total number of students in the class?

A. 4:7
B. 16:28
C. 3:5
D. 2:3

Correct answer: A

Rationale: To find the ratio of women to the total number of students, you need to simplify the ratio of 16:28. By dividing both numbers by the greatest common factor, which is 4, you get 4:7. Therefore, the correct ratio of women to the total number of students is 4:7. Choice A is correct. Choices C and D are incorrect because they do not represent a valid ratio. Choice B is the original ratio given in the question, which should be simplified to 4:7 as explained in the rationale.

4. What is the result of dividing 2,032 by 25?

A. 91 r3
B. 81 r28
C. 81 r7
D. 9 r3

Correct answer: C

Rationale: When dividing 2,032 by 25, you find that 25 goes into 2,032 a total of 81 times without exceeding it. The remainder is 7, not 28 as stated in choice B. This is because 25 * 81 = 2,025, leaving a difference of 7, not 28. Choice A and D are incorrect because they do not correctly represent the division result of 2,032 by 25.

5. 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.