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. Eighty percent of the class passed with a 75 or higher. If that percentage equals 24 students, how many students were in the whole class?

Correct answer: C

Rationale: If 80% of the class passed with a 75 or higher, and that equals 24 students, you can set up a proportion to find the total number of students in the class. Since 80% is equal to 24 students, 100% (the whole class) would be equal to (24/80) x 100 = 30 students. Therefore, the total number of students in the whole class is 30 / 80 x 100 = 36. Choice A (18) is incorrect as it does not match the calculation based on the information given. Choice B (30) is incorrect because it represents the intermediate calculation but not the total number of students in the class. Choice D (60) is incorrect as it is double the correct answer and does not align with the given information.

3. A label states 1 mil contains 500 mg. How many mils are there if there are 1.5 grams?

Correct answer: C

Rationale: To calculate the number of mils, first, convert 1.5 grams to milligrams (1.5 grams = 1500 mg). Then, since 1 mil contains 500 mg, divide 1500 mg by 500 mg/mil, resulting in 3 mils required to contain 1.5 grams of substance. Choice A, 9, is incorrect because it miscalculates the conversion. Choice B, 2, is incorrect as it does not consider the correct conversion factor. Choice D, 5, is incorrect as it also miscalculates the conversion.

4. After the young mother goes shopping and spends $101.85 on groceries, $21.90 at the dry cleaners, and $42.66 at the pet store, she has $200.00 in cash. How much money would she have left after her day of shopping?

Correct answer: A

Rationale: The correct answer is A, $33.59. To find out how much money she would have left, we need to calculate the total spending by adding the amounts spent at the groceries, dry cleaners, and pet store: $101.85 + $21.90 + $42.66 = $166.41. Subtract the total spending from the initial cash amount to determine the remaining cash: $200.00 - $166.41 = $33.59. Choice B, $29.59, is incorrect as it does not accurately reflect the correct calculation. Choices C and D, $25.59 and $21.59 respectively, are also incorrect as they do not consider the correct total spending amount and subtraction from the initial cash.

5. Add 2\3 + 1\6 + 2\5.

Correct answer: A

Rationale: To add fractions, find a common denominator (30), which gives 20/30 + 5/30 + 12/30=37/30= 1 7/30

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