Question

A chemist has a 40% alcohol solution and a 25% alcohol solution. How much of each should he mix together to get 50 liters of a 35% alcohol solution?

Answer 1

33 1/3 L of the 40% solution, 16 2/3 L of the 25% solution

Explanation:

Set up two equations...

Let x represent the number of Liters of the 40% solution

Let y represent the number of Liters of the 25% solution

We need 50 liters total, so

x + y = 50

and we need the 50 L to be 35% solution, so

0.4x = 0.25y = 0.35(50)

Solve the first equation for one variable...

x = 50 - y (subtract y from both sides in equation 1)

Now substitute that value into the second equation...

0.4(50 - y) + 0.25y = 17.5 (x becomes 50 - y, 0.35(50) = 17.5)

Now solve for y...

20 - 0.4y + 0.25y = 17.5

-0.15y = -2.5

y = 16.66666667

y = 16 2/3 L

So we need to plug that into the first equation to find 'x'

x + 16 2/3 = 50

x = 50 - 16 2/3

x = 33 1/3