A beaker full of hot water is kept in a room. It cools from ${80}^{\circ }\mathrm{C}\text{ to }{75}^{\circ }\mathrm{C}\text{ in }{\mathrm{t}}_1$ minutes, 75° C to 70°C in t₂ minutes and ${70}^{\circ }\mathrm{C}\text{ to }{65}^{\circ }\mathrm{C}\text{ in }{\mathrm{t}}_3$ minutes in the same surroundings. Then

As per Newton's law of cooling, rate of cooling of a body is directly proportional to difference of temperature of body and that of surrounding. So body cools down relatively quickly at higher temperatures than at lower temperatures.

Hence, ${\mathrm{t}}_1<{\mathrm{t}}_2<{\mathrm{t}}_3$