His heart was beating 24 beats every 10 seconds.
We have to calculate how many times would his heart beat in 3 minutes.
Knowing that one minute is 60 seconds, we can start by calculating how many seconds are represented in 3 minutes:
[tex]3\min \cdot\frac{60s}{1\min}=3\cdot60s=180s[/tex]Three minutes are equal to 180 seconds. Then, we can apply the rule of three: if 10 seconds correspond to 24 heart beats, we can calculate the number of heart beats in 180 seconds as
[tex]\begin{gathered} 10s\longrightarrow24\text{ beats} \\ 180s\longrightarrow x=180\cdot\frac{24}{10}=180\cdot2.4=432\text{ beats} \end{gathered}[/tex]Answer: In three minutes, his heart will beat 432 times.
