Convert each part of the Ratio to Percentage:

1:2:5

The sum of ratio = 1+2+5 = 8

First part = $\frac{1}{8}$

Second part = $\frac{2}{8}$

Third part = $\frac{5}{8}$

Percentage of first part =$\frac{1}{8}\times 100$= 12.5%

Percentage of second part =$\frac{2}{8}\times 100$= 25%

Percentage of third part =$\frac{5}{8}\times 100$= 62.5%