Newton's Law of Cooling states that the rate of cooling of an object is proportional to the temperature difference between the object and its surroundings (provided the difference is not too large).

Example 3: A hard-boiled egg at 98°C is put in a pan under 18°C running water to cool. After 5 minutes, the egg's temperature is found to be 38°C. How much longer will it take for the egg to reach 20°C?

Newton's Law of Cooling