a lab needs 200ml of a 5 salt solution they only have a 10 solution how much 10 solution and water should be mixed
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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?

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. How many kilograms are there in 11 pounds?

Correct answer: B

Rationale: To convert pounds to kilograms, you can use the conversion factor: 1 pound is approximately equal to 0.453592 kilograms. Therefore, 11 pounds is equal to 11 * 0.453592 = 4.989512, which is approximately 5.5 kilograms. The correct answer is 5.5 kilograms. Choice A is incorrect as it rounds down and doesn't account for the decimals in the conversion. Choices C and D are significantly higher than the correct answer and are clearly incorrect conversions.

3. How many cakes do you need for a class of 70 students and 3 staff members if each cake provides 24 servings?

Correct answer: A

Rationale: To determine the number of cakes needed, calculate the total number of people, which is 70 students + 3 staff = 73 people. Since each cake serves 24 people, divide the total number of people by 24 to get approximately 3.04. You cannot have a fraction of a cake, so round up to the next whole number, which is 4. Therefore, you need 4 cakes to serve the class of 70 students and 3 staff members. Choice B (2) is incorrect because 2 cakes would not be enough to serve 73 people. Choice C (5) is incorrect as it would be an excess of cakes. Choice D (3) is incorrect because 3 cakes would not be sufficient to serve 73 people.

4. The metric system of measurement was developed in France during Napoleon's reign. It is based on what multiplication factor?

Correct answer: C

Rationale: The metric system is based on powers of 10, making calculations and conversions easier because each unit increases or decreases by a factor of 10.

5. What is 70% of 65?

Correct answer: B

Rationale: To find 70% of 65, you multiply 0.7 by 65. Mathematically, 0.7 * 65 = 45.5. Therefore, the correct answer is 45.5. Choice A (40.5) is incorrect because it is not the result of multiplying 0.7 by 65. Choice C (50) is incorrect as it is higher than the correct answer. Choice D (55) is also higher than the correct result and is therefore incorrect.

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