Question

Arnold needs a 25% solution of nitric acid. He has 20 milliliters (ml) of a 30% solution. How many ml of a 15% solution should he add to obtain the required 25% solution?

Answer 1

`10` ml of `15%` solution to be added to get `25%` solution.

Explanation:

In `20`ml of `%30%`nitric acid solution, nitric acid content is `20*(0.3)=6 ml`. Let `x` ml of `15%` solution is added. So nitric acid content in `(20+x)` ml solution is `6+.15x`, Now by condition, `6+.15x=0.25(20+x) or 6+.15x = 5+ .25x or .1x= 1 :. x=10 ml`[Ans]