A body cools from `80°C` to `50°C` in `5minutes`,Calculate the time it taken to cool from `60°C` to `30°C`.The temperature of the surrounding is `20°C`.

A first order reaction is 20% complete in 5 minutes. Calculate the time taken for the reaction to be 60% complete

​Sitha prepares tea for her brother. After preparing tea, the temperature of the tea was 80°C. She kept it for 5 minutes and gave to her brother when the temperature reached 50°C. If the surrounding temperature is 20°C, calculate the time it takes to cool from 60°C to 30°C.