What percent of water should be evaporated to obtain a 0.6 M KOH solution?

Question

A 0.2 M KOH solution has a volume of 3 L.

What percent of water should be evaporated to obtain a 0.6 M KOH solution? 

Answer 1

V1M1 = V2M2

(3 L)(0.2 M) = (x L)(0.6 M)

x = 1 L

So, final volume should be 1 L which means the volume of water that needs to be evaporated = 2 L.

As a percentage, this would be 2/3 = 0.667 = 66.7% should be evaporated.