Question

A cup of hot water is left out to cool. The water is currently 70 Degrees C above room temperature. If the heat difference decreases by 5% every minute, what will be the difference in 15 minutes? Round to nearest tenth.

Answer 1

We were given the following information:

A cup of hot water is left out to cool

The water is currently 70 Degrees

Heat difference decreases by 5% every minute = 5% = 5/100 = 0.05

In 15 minutes, the temperature of the water is given by:

`\begin{gathered} T_{}=70-0.05x \\ when\colon x=15 \\ T=70-0.05(15) \\ T=70-0.75 \\ T=69.25\approx69.3 \\ \\ \therefore T=69.3(to\text{ the nearest tenth)} \end{gathered}`