Question

A certain quantity of 40% solution is replaced with 25% solution such that the new concentration is 35%. What is the fraction of the solution that was replaced?

Answer 1

Answer:

1/3 fraction of the solution  was replaced

Step-by-step explanation:

Let say solution was  100 L

40% of Solution = 40 L

Remaining = 60L

Let say it is replaced with 100X of 25% solution

25% of solution = 25X

Remaining = 70X

as 100X is Replaced so

from 1st solution

40X  of solution is removed  

Solution remains = 40L - 40X  + 25X   = 40L - 15X

Total = 100L

New concentration = 35%

=>100 *  (40L - 15X)/100L = 35

=> 40L - 15X = 35L

=> 5L = 15X

=> X/L  = 5/15

=> X/L = 1/3

=> 100X/100L = 1/3

1/3 fraction of the solution  was replaced