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 meters are in 2 kilometers?

Correct answer: C

Rationale: 1 kilometer equals 1,000 meters. Therefore, 2 kilometers equals 2,000 meters. Choice A, 100 meters, is incorrect as it represents only 1/10th of a kilometer. Choice B, 200 meters, is incorrect as it represents only 1/5th of a kilometer. Choice D, 3000 meters, is incorrect as it miscalculates the conversion from kilometers to meters.

3. A farmer buys 3 bags of feed weighing 50 kilograms each. How much feed does he have in total?

Correct answer: B

Rationale: The correct answer is B: 150 kilograms. To find the total amount of feed, you need to multiply the number of bags by the weight of each bag. In this case, 3 bags * 50 kilograms each = 150 kilograms. Therefore, the farmer has a total of 150 kilograms of feed. Choice A (100 kilograms) is incorrect because it doesn't consider the total weight of all 3 bags. Choice C (200 kilograms) and Choice D (250 kilograms) are incorrect as they are miscalculations of the total weight of the feed.

4. Solve for x. x/250 = 3/500

Correct answer: A

Rationale: To solve the proportion x/250 = 3/500, cross multiply to get 500x = 750. Then solve for x by dividing both sides by 500, which results in x = 1.5. Therefore, the correct answer is A. Choice B (2) is incorrect because the correct solution is 1.5, not 2. Choice C (1500) is incorrect as it does not align with the correct calculation of the proportion. Choice D (25) is incorrect and does not match the correct solution obtained by solving the proportion.

5. A medication must be taken twice daily, 12 hours apart. If the first dose is at 8:00 AM, what is the most convenient time for the second dose to avoid disrupting sleep?

Correct answer: B

Rationale: To take the medication 12 hours apart from the first dose at 8:00 AM, the second dose should be taken at 8:00 PM. However, to avoid disrupting sleep, it is recommended to take the second dose a bit earlier. Taking the second dose at 6:00 PM ensures that the medication is still being taken 12 hours apart while allowing for a buffer before bedtime to avoid any potential disruptions to sleep. Choice A (4:00 PM) is too early, not maintaining the 12-hour interval. Choice C (8:00 PM) aligns with the 12-hour interval but might be too close to bedtime, potentially causing sleep disruptions. Choice D (10:00 PM) is too late and exceeds the 12-hour interval.

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