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. The physician ordered 20 mg of Tylenol per kg of body weight; on hand is 80 mg per tablet. The child weighs 12 kg. How many tablets will you give?

Correct answer: B

Rationale: To calculate the total dose of Tylenol for the child weighing 12 kg, multiply the weight by the ordered dose: 12 kg x 20 mg/kg = 240 mg. Since each tablet contains 80 mg of Tylenol, divide the total dose needed by the amount per tablet: 240 mg ÷ 80 mg/tablet = 3 tablets. Therefore, the correct answer is 3 tablets. Choices A, C, and D are incorrect because they do not reflect the accurate calculation for the number of tablets required based on the child's weight and the ordered dose per kg.

3. If 9 out of 75 band members missed practice, what percentage of band members missed practice?

Correct answer: B

Rationale: To calculate the percentage of band members who missed practice, divide the number of members who missed practice (9) by the total number of band members (75) and multiply by 100. (9/75) * 100 = 12%. Therefore, 12% of the band members missed practice. Choice A (10%) is incorrect because it is not the correct calculation result. Choices C (15%) and D (18%) are also incorrect as they do not reflect the accurate percentage of band members who missed practice.

4. What is the result of the addition: 34 + 4 + 234?

Correct answer: D

Rationale: Adding the given numbers together: 34 + 4 + 234 = 272. The correct sum is 272. Choice A, 70.2, is incorrect as it does not reflect the accurate addition of the numbers. Choice B, 230.72, is incorrect as well. Choice C, 234.74, is also incorrect since the correct sum is 272, not 234.74.

5. How many milliliters are in 1 liter?

Correct answer: B

Rationale: There are 1,000 milliliters in 1 liter. The prefix 'milli-' means one-thousandth, so when converting from liters to milliliters, you multiply by 1,000. Therefore, the correct answer is 1,000 mL. Choice A (100 mL) is incorrect as it represents one-tenth of the correct conversion. Choice C (500 mL) is incorrect as it is half of the correct conversion. Choice D (50 mL) is incorrect as it is one-twentieth of the correct conversion.

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