Question

An ice is melt at the rate which is proportional to amount of ice present that instant if half the quantity ice melt in 20 min. Show that $\frac{1}{8}$ of the original amount of ice will be left after one hour.

Answer 1

$\frac{1}{8}$ can be written as $\frac{1}{2}\times \frac{1}{2}\times \frac{1}{2}$ for melting $\frac{1}{2}$ of ice $20$ minutes is required.

Hence $20+20+20=60minutes=1hr$