We know that the temperature changes 16/25 degrees in 1/2 second. To find how long it will take the liquid to cool 40 degrees we can use the rule of three:
[tex]\begin{gathered} \frac{16}{25}\rightarrow\frac{1}{2} \\ 40\rightarrow x \end{gathered}[/tex]Then:
[tex]x=\frac{40\cdot\frac{1}{2}}{\frac{16}{25}}=\frac{\frac{40}{2}}{\frac{16}{25}}=\frac{125}{4}[/tex]Therefore it takes 125/4 seconds (or 31.25 seconds) to cool the liquid 40 degress.
