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 man is reading a book with 798 pages. If he reads 2 chapters a day and each chapter has 6 pages, how many days will it take him to finish the book?

Correct answer: C

Rationale: To find the total number of chapters, divide the total number of pages by the number of pages per chapter: 798 ÷ 6 = 133 chapters. Reading 2 chapters per day means it will take 133 ÷ 2 = 66.5 days. Choice A, 133 days, is incorrect because it miscalculates the days needed to finish the book. Choice B, 399 days, is incorrect as it doesn't consider the number of chapters read per day. Choice D, 75 days, is incorrect as it doesn't account for the total number of chapters in the book.

3. Last night at the hospital, 76 babies were born. Of the births, 45% were girls. How many boys were born last night? (Round your numbers to the nearest whole number).

Correct answer: A

Rationale: When 45% of the babies were girls, it means the remaining 55% were boys. To determine the number of boys, calculate 55% of 76, which equals approximately 41.8, rounding up to 42. Therefore, 42 boys were born last night at the hospital. Choice B, C, and D are incorrect as they do not reflect the accurate calculation of the number of boys born.

4. There are 6,657 marbles in a jar. Approximately 34% are white, and the rest are black. How many black marbles are there?

Correct answer: A

Rationale: To find the number of black marbles, we need to calculate the percentage that represents the black marbles, which is 100% - 34% = 66%. Then, we find 66% of 6,657 to determine the number of black marbles. 66% of 6,657 is approximately 4,394, so there are 4,394 black marbles in the jar. Choice A is correct. Choices B, C, and D are incorrect as they do not reflect the correct calculation for the number of black marbles in the jar.

5. What is the result of adding 1/2 + 4/5?

Correct answer: A

Rationale: To add fractions, you need a common denominator. In this case, the common denominator is 10. So, 1/2 + 4/5 = 5/10 + 8/10 = 13/10 = 1 3/10. Therefore, the correct answer is A: 1 3/10. Choice B, 1/2/2024, is incorrect as it does not represent the sum of the fractions given. Choice C, 1 2/5, is incorrect as it does not match the sum calculated. Choice D, 1 1/5, is incorrect as it does not reflect the correct sum of the fractions provided.

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