Answer:
1.333 beats/s
It takes 0,755 s per beat
Step-by-step explanation:
If we want to convert this frequency from beats per minute to beats per second, we have to do the following:
![80(beats)/(min) (1min)/(60s)=1.333(beats)/(s)](https://img.qammunity.org/2020/formulas/physics/middle-school/1kgpk1xfrg56tomc9e7gplghzdb6i37kei.png)
This means that in 1 second David has 1.333 heart beats.
Now, if we want to know how long does it take between heart beats, we can use the mathematical Rule of Three:
1.333 beats ---- 1s
1 beat ------ ?
![?=((1 beat)(1s))/(1.333 beats)](https://img.qammunity.org/2020/formulas/physics/middle-school/l7xvv1y0e5e4cl54nwu9a0fufai382ncuj.png)
This means there are 0.75 s between heart beats