a lab needs 200ml of a 5 salt solution they only have a 10 solution how much 10 solution and water should be mixed

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?

A. 100ml 10% solution, 100ml water
B. 150ml 10% solution, 50ml water
C. 160ml 10% solution, 40ml water
D. 200ml 10% solution, 0ml water

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. Stu purchased a set of 6 cups and 6 plates at a garage sale. The cups were 25 cents each, and the plates were 75 cents each. If Stu paid with a $10 bill, how much change was he owed?

A. $4
B. $4.50
C. $5
D. $5.50

Correct answer: C

Rationale: Stu purchased 6 cups at 25 cents each, totaling $1.50 (6 cups x $0.25 = $1.50). He also bought 6 plates at 75 cents each, totaling $4.50 (6 plates x $0.75 = $4.50). Therefore, the total cost of the cups and plates is $1.50 + $4.50 = $6. Stu paid with a $10 bill, so the change he was owed is $10 - $6 = $4. Stu was owed $4 in change. The correct answer is $5, not $4 as he was owed that amount. Option A, $4, is incorrect as it miscalculates the change amount. Option B, $4.50, is incorrect as it does not consider the correct total cost. Option D, $5.50, is incorrect as it overestimates the change Stu was owed.

3. Olivia’s Bakery gives out one extra cupcake for each dozen sold, to make a “baker’s dozen” of 13 in all. How many extra cupcakes does the bakery add to a special order of 180 cupcakes?

A. 12
B. 13
C. 14
D. 15

Correct answer: B

Rationale: Olivia’s Bakery gives out one extra cupcake for each dozen sold. For a special order of 180 cupcakes, there would be 180 cupcakes ÷ 12 cupcakes per dozen = 15 dozens. Therefore, the bakery adds 15 extra cupcakes to make a 'baker's dozen' of 13 in all for each dozen, resulting in a total of 15 extra cupcakes added to the special order. The correct answer is 13 (choice B) because the bakery adds one extra cupcake to each dozen, making a 'baker's dozen' of 13.

4. Multiply and express as a decimal: 6 × 55 =

A. 0.0033
B. 0.033
C. 0.33
D. 3.3

Correct answer: D

Rationale: To find the result of multiplying 6 by 55, you perform the operation 6 × 55, which equals 330. To express this product in decimal form, you place the decimal point one place from the right, resulting in 3.3. Therefore, the correct answer is D (3.3). Choices A, B, and C are incorrect as they do not represent the correct decimal equivalent of the multiplication of 6 and 55.

5. What is the result of dividing 4 7/8 by 1 1/6?

A. 4 5/28
B. 4 7/8
C. 5 8/14
D. 5 3/28

Correct answer: A

Rationale: To divide mixed numbers, convert them to improper fractions and then multiply by the reciprocal of the divisor. Here, 4 7/8 = 39/8 and 1 1/6 = 7/6. Dividing 39/8 by 7/6 gives 39/8 ÷ 7/6 = 39/8 * 6/7 = 234/56 = 4 5/28. Therefore, the correct answer is A. Choices B, C, and D are incorrect as they do not represent the correct result of dividing 4 7/8 by 1 1/6.