• Subject:

...

• Topic:

...

A body takes 5 minutes to cool from 90$°\mathrm{C}$ to 60$°\mathrm{C}$. If the temperature of the surroundings is 20$°\mathrm{C}$, the time taken by it to cool from 60$°\mathrm{C}$ to 30$°\mathrm{C}$ will be.
(a) 5 min                    (b) 8 min
(c) 11 min                   (d) 12 min