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. What is the average of the numbers 14, 73, and 7?

Correct answer: D

Rationale: The correct answer is D. Adding 14 + 73 + 7 gives a total of 94. To find the average, we divide the sum by the number of values (3), which equals 31.33. Rounding this average to two decimal places gives us 31.33, which corresponds to option D. Choices A, B, and C are incorrect as they do not correctly calculate the average of the given numbers. Choice A is close to the sum of the numbers, not the average. Choices B and C are also not correct averages calculated from the provided numbers.

3. Convert 5 3/4 to a decimal. Round to the nearest tenth.

Correct answer: C

Rationale: To convert 5 3/4 to a decimal, we add the whole number part to the fractional part: 5 + 3/4 = 5.75. Rounding 5.75 to the nearest tenth gives us 5.8. Therefore, the correct answer is C. Choice A (5.6) is incorrect because it does not accurately represent 5 3/4. Choice B (5.7) is incorrect as well because it does not reflect the correct conversion. Choice D (6) is incorrect as it does not account for the fractional part of 5 3/4.

4. A nurse needs to administer 0.8 milliliters of medication. The only available syringe measures in teaspoons. How many teaspoons should the nurse use?

Correct answer: B

Rationale: 1 milliliter is approximately equal to 0.2 teaspoons. To find out how many teaspoons are in 0.8 milliliters, we can set up a proportion: 0.8 milliliters * 0.2 teaspoons/1 milliliter = 0.16 teaspoons. Since 0.16 teaspoons is not one of the answer choices, we need to convert it to a more practical measurement. The closest option is 0.4 teaspoons, making it the correct answer. Choice A, 0.2 teaspoons, is incorrect because 0.8 milliliters is more than that. Choices C and D, 0.6 teaspoons and 0.8 teaspoons, respectively, are also incorrect based on the conversion factor of 1 milliliter to 0.2 teaspoons.

5. In a class of 25 students, 44% are boys. How many boys are there?

Correct answer: B

Rationale: To find the number of boys in the class, calculate 44% of 25 students. 44% of 25 is calculated as follows: 0.44 x 25 = 11 boys. Therefore, there are 11 boys in the class. Choice A, 10 boys, is incorrect as it miscalculates the percentage. Choice C, 9 boys, is incorrect as it is less than 11. Choice D, 13 boys, is incorrect as it is greater than the correct calculation.

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