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. A vitamin's expiration date has passed. It was supposed to contain 500 mg of calcium, but it has lost 325 mg of calcium. How many mg of calcium are left?

Correct answer: A

Rationale: The correct answer is A: 175 mg. The vitamin originally contained 500 mg of calcium. After losing 325 mg, the remaining amount of calcium is calculated as 500 mg - 325 mg = 175 mg. Choice B (135 mg) is incorrect because the vitamin lost more calcium than that. Choices C (185 mg) and D (200 mg) are incorrect as they do not consider the amount of calcium lost from the original 500 mg.

3. What is (12/15) ÷ (3/5) = ?

Correct answer: A

Rationale: To divide fractions, you multiply by the reciprocal of the divisor. (12/15) ÷ (3/5) is the same as (12/15) * (5/3). Cancel out common factors to simplify: 12 ÷ 3 = 4, 15 ÷ 5 = 3. So, the expression simplifies to 4/3, which is 1 1/3 in mixed number form. Choice A, 1 1/3, is the correct answer. Choices B, C, and D are incorrect because they do not represent the simplified form of the division of the given fractions.

4. 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.

5. Edie has 132 tulip bulbs. She wants to plant all of the tulip bulbs in 12 rows. How many bulbs should she plant in each row?

Correct answer: A

Rationale: To plant 132 bulbs in 12 rows, Edie should plant 11 bulbs in each row. This is calculated by dividing the total number of bulbs by the number of rows: 132 bulbs ÷ 12 rows = 11 bulbs per row. Choice B, 10 bulbs, is incorrect because dividing 132 bulbs by 12 rows does not equal 10. Choice C, 12 bulbs, is incorrect because if Edie plants 12 bulbs in each row, the total number of bulbs planted would exceed 132. Choice D, 15 bulbs, is incorrect as dividing 132 bulbs by 12 rows does not result in 15 bulbs per row.

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