How much of each solution will she require to make a resulting solution that has 25 liters and has a 28% concentration?

Question

Ms. Hayden is mixing up a solution for biology. Solution A has a 40% concentration and solution B has a 20% concentration. 

Answer 1

The solution to this question involves the formula C1V1 + C2V2 = C3V3

where C = Concentration and V = Volume

 

First, we will convert the percentages to decimals, so 20% = 0.2, 28% = 0.28, and 40% = 0.4

 

Let x = Volume of 40% solution which will be diluted using the 20% solution

 

0.4x + 0.2(25L - x) = 0.28·25L

expanding, we get 0.4x + 5L - 0.2x = 7L

combining, we get 0.2x = 7L - 5L

then x = 2L/0.2 = 10L

 

so, we will need 10L of 40% which will be diluted with 15L of 20% to yield 25L of 28%

 

roof: 10L · 40% + 15L · 20% = 25L · 28%; 4L + 3L = 7L