A body in a room cools from 85∘c  to  80∘c in 5 minutes. The time taken to cool from 80∘c  to  75∘c is

θ1=85∘c    θ2=80∘cθ2=80∘c    θ3=75∘ct1=5 minutest2=?θ0=constant=temperature of surrounding  from newton law of cooling  dθdt1=-kθ1+θ22-θ0---(1)  substitute given values in above equationθ1-θ25=-k85+802-θ085-805=-k82.52-θ055=-k41.25-24---(2)∵Room temperature is 24°C  second part of question, given values substitute in eqn(1)80-75t2=-k80+752-θ05t2=-k38.75-24---(3)  eqn(2) ÷eqn(3)  t2= 5.47mint2is more than 5 minutes