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. What number is 15, if it is 20% of that number?

A. 3
B. 45
C. 75
D. 300

Correct answer: B

Rationale: To find the number that 15 is 20% of, we set up the equation: x * 0.20 = 15. Solving for x, we get x = 15 / 0.20 = 75. Therefore, 15 is 20% of 75. Choice A, 3, is too small to be 20% of 15. Choice C, 75, is the result of the correct calculation. Choice D, 300, is too large to be 20% of 15.

3. Change 1/6 to a percent.

A. 16.67%
B. 15%
C. 14%
D. 17%

Correct answer: A

Rationale: To convert 1/6 to a percentage, you multiply 1/6 by 100. This gives you 16.67%. Choice A is correct. Choice B, 15%, is incorrect as it is the rounded value of 1/6 as a percentage. Choice C, 14%, and Choice D, 17%, are also incorrect as they do not represent the accurate conversion of 1/6 to a percentage.

4. How many feet are in 2 miles?

A. 5280 feet
B. 15840 feet
C. 10560 feet
D. 10200 feet

Correct answer: C

Rationale: To convert miles to feet, multiply the number of miles by the conversion factor of feet per mile. Since there are 5280 feet in 1 mile, to find the number of feet in 2 miles, you multiply 2 by 5280, resulting in 10560 feet. Choice A, 5280 feet, is the conversion factor for 1 mile, not for 2 miles. Choices B and D are incorrect calculations that do not follow the conversion factor correctly.

5. Subtract and simplify: 8¼ − 1½.

A. 4¼
B. 6¾
C. 6⅞
D. 7¼

Correct answer: A

Rationale: To subtract mixed numbers, convert them to improper fractions. 8¼ = 33/4 and 1½ = 3/2. Subtracting, we get 33/4 - 3/2 = 33/4 - 6/4 = 27/4 = 6¾, which simplifies to 4¼. Therefore, the correct answer is 4¼. Choice B is incorrect as it represents the intermediate step of 6¾ before simplification. Choice C is incorrect as it is the result of the subtraction but not simplified. Choice D is incorrect as it is the original mixed number 7¼, not the simplified result.