An ordinary body cools from $4\theta$ to $3\theta$ in $t$ minutes. The temperature of the body after the next $t$ minutes is (Assume Newton's law of cooling and room temperature as $\theta$).

According to Newton's law of cooling,the rate of cooling of a body is directly proportional to the ........

$A$ body cools down from $75^{\circ}C$ to $60^{\circ}C$ in $10 \text{ minutes}$. It will cool down from $65^{\circ}C$ to $55^{\circ}C$ in a time:

$A$ cup of tea cools from $80\,^{\circ}C$ to $60\,^{\circ}C$ in $1$ minute. The ambient temperature is $30\,^{\circ}C$. How long will it take to cool from $60\,^{\circ}C$ to $50\,^{\circ}C$?

Four spheres $A, B, C$ and $D$ are of the same radius but made of different metals. Their densities are in the ratio $6 : 3 : 4 : 5$ and specific heats are in the ratio $2 : 5 : 4 : 6$. These are initially kept at the same temperature and placed in the same surroundings. The sphere which has the slowest rate of cooling is

$A$ body takes $5$ minutes for cooling from $50^oC$ to $40^oC$. Its temperature comes down to $33.33^oC$ in the next $5$ minutes. The temperature of the surroundings is ....... $^oC$.