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. Lulu is 5 years younger than her sister, who is 7 years older than their 15-year-old cousin. How old is Lulu?

A. 27
B. 22
C. 19
D. 17

Correct answer: C

Rationale: Let Lulu's sister's age be x. According to the given information, x = 15 (cousin's age) + 7 = 22. So, Lulu's sister is 22 years old. Since Lulu is 5 years younger than her sister, Lulu's age is 22 - 5 = 17. Therefore, Lulu is 17 years old. Choices A, B, and D are incorrect because they do not correspond to the calculations based on the information provided in the question.

3. Convert 0.007 kilograms to grams.

A. 7 grams
B. 70 grams
C. 0.07 grams
D. 0.70 grams

Correct answer: A

Rationale: To convert kilograms to grams, you need to multiply by 1000 since there are 1000 grams in a kilogram. Therefore, 0.007 kilograms is equal to 0.007 x 1000 = 7 grams. Choice A is correct. Choice B is incorrect as it incorrectly multiplies by 10 instead of 1000. Choice C is incorrect as it incorrectly moves the decimal point one place to the right. Choice D is incorrect as it incorrectly moves the decimal point two places to the right.

4. A circular bandage has a diameter of 6cm. What is the area covered by the bandage (area of a circle = πr^2)?

A. 9π cm^2
B. 18π cm^2
C. 27π cm^2
D. 36π cm^2

Correct answer: C

Rationale: Rationale: - The formula for the area of a circle is A = πr^2, where r is the radius of the circle. - The diameter of the circular bandage is 6 cm, so the radius (r) is half of the diameter, which is 6/2 = 3 cm. - Substitute the radius (r = 3 cm) into the formula for the area of a circle: A = π(3)^2 = 9π cm^2. - Therefore, the area covered by the bandage is 9π cm^2.

5. What percentage of her income is left after Mary spent 15%?

A. 12%
B. 85%
C. 75%
D. 95%

Correct answer: B

Rationale: To determine the percentage of income remaining after spending 15%, subtract the percentage spent from 100% (100% - 15% = 85%). Therefore, Mary has 85% of her income left, which aligns with answer choice B. Choice A (12%) is incorrect because it represents the remaining amount after spending 88% of her income. Choice C (75%) is incorrect as it does not account for the 15% already spent. Choice D (95%) is incorrect as it does not consider the amount spent by Mary.