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. A nurse working at the hospital earns $22 per hour. She worked two 12-hour shifts and two 8-hour shifts during the week. How much did she earn for the week?

A. $960
B. $1,080
C. $990
D. $880

Correct answer: A

Rationale: The nurse worked a total of 40 hours (2 x 12 hours + 2 x 8 hours) during the week. Multiplying 40 hours by her hourly rate of $22 gives a total earning of $960 for the week. Therefore, the correct answer is $960. Choice B ($1,080) is incorrect because it miscalculates the earnings by adding extra hours. Choice C ($990) is incorrect as it does not account for the correct number of hours worked. Choice D ($880) is incorrect as it underestimates the total earnings by not considering all hours worked.

3. Multiply 12 by 15 and express the result as a decimal:

A. 0.0018
B. 0.018
C. 0.18
D. 1.8

Correct answer: D

Rationale: To find the product of 12 and 15, you simply multiply them together. 12 multiplied by 15 equals 180. To express 180 as a decimal, you divide by 100. Therefore, the correct answer is 1.8. Choices A, B, and C are incorrect as they represent values that are not the correct result of multiplying 12 by 15 and converting it to a decimal.

4. Sally was able to eat 5/8 of her lunch. John ate 75% of his lunch. Who ate more of their meal?

A. Sally
B. John
C. Neither
D. Both

Correct answer: B

Rationale: To compare who ate more of their meal, we need to convert the fractions to the same format. John ate 75% of his lunch, which is equivalent to 3/4. Sally ate 5/8 of her lunch. Comparing 3/4 to 5/8, we find that 3/4 is greater than 5/8. Therefore, John ate more of his meal than Sally. Choice B, John, is the correct answer. Choices A, C, and D are incorrect because John consumed 3/4 of his lunch, which is more than 5/8 that Sally consumed, making him the one who ate more of his meal.

5. What is (12/15) ÷ (3/5) = ?

A. 1 1/3
B. 1 2/3
C. 2 1/3
D. 1

Correct answer: A

Rationale: To divide fractions, you multiply by the reciprocal of the divisor. (12/15) ÷ (3/5) is the same as (12/15) * (5/3). Cancel out common factors to simplify: 12 ÷ 3 = 4, 15 ÷ 5 = 3. So, the expression simplifies to 4/3, which is 1 1/3 in mixed number form. Choice A, 1 1/3, is the correct answer. Choices B, C, and D are incorrect because they do not represent the simplified form of the division of the given fractions.