Question

A scientist needs 10 liters of a 20% acid solution for an experiment, but she only has a 5% solution and a 40% solution. To the nearest tenth of a liter, about how many liters of the 5% and 40% solutions should she mix to get the solution she needs?

Answer 1

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Answer:

• 4.3 L of 40% solution
• 5.7 L of 5% solution

Explanation:

Let x represent the number of liters of 40% solution in the mix. Then the total amount of acid in the mix is ...

0.40x +0.05(10-x) = 0.20(10)

0.35x +0.5 = 2.0

0.35x = 1.5

x = 1.5/0.35 ≈ 4.3 . . . . liters of 40% solution

10-x = 10 -4.3 = 5.7 . . .liters of 5% solution