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. Convert the following decimal to a percent: 0.0068

A. 0.68
B. 6.8
C. 0.068
D. 0.0068

Correct answer: A

Rationale: To convert a decimal to a percent, move the decimal point two places to the right. Therefore, 0.0068 as a percentage is 0.68%. Choice A is correct because it represents the correct conversion. Choice B is incorrect as it would be the decimal 6.8 represented as a percentage. Choice C is incorrect as it would be the decimal 0.068 represented as a percentage. Choice D is incorrect as it is the original decimal value.

3. If he left a tip of $36 on a total bill of $200, what percentage of the total bill did he leave as a tip?

A. 16%
B. 18%
C. 20%
D. 22%

Correct answer: B

Rationale: To determine the tip percentage left, divide the tip amount ($36) by the total bill amount ($200), then multiply the result by 100 to express it as a percentage: (36/200) x 100 = 18%. Therefore, he left an 18% tip on the total bill amount. Choice A (16%) is incorrect because the correct calculation results in 18%. Choice C (20%) and Choice D (22%) are incorrect as they do not match the calculated percentage based on the provided numbers.

4. A runner leaves at 7:45 for a morning run at an average speed of 6 mph and returns at 10:00. How many miles did he run?

A. 11.5 miles
B. 14.5 miles
C. 12 miles
D. 13.5 miles

Correct answer: D

Rationale: The runner left at 7:45 and returned at 10:00, which means he ran for 2 hours and 15 minutes (10:00 - 7:45). At an average speed of 6 mph, in 2.25 hours, he would have covered 6 mph * 2.25 hours = 13.5 miles. Therefore, the correct answer is 13.5 miles. Choices A, B, and C are incorrect because they incorrectly calculate the distance based on the time and speed provided in the question.