# College Physics Problem 1.15

## Solution:

### Part a

This is a problem on rounding off. Take note that 72.0 has three significant figures, 2.0 has two significant figures, 2.00 has three significant figures, and 2.000 has four significant figures.

In 2 years, the number of beats of an average person is

$\displaystyle \left(\frac{72.0\:beats}{1\:min}\right)\left(\frac{60.0\:min}{1.00\:hr}\right)\left(\frac{24.0\:hr}{1.00\:day}\right)\left(\frac{365.25\:days}{1\:year}\right)$

$\displaystyle =7.5738\times 10^7\:beats$

For item letter a), the answer is limited by 2.0, which is 2 significant figures. The answer is $7.6\times 10^7\:beats$.

### Part b

For item letter b), the answer is limited by 2.00, which is 3 significant figures. The answer is $7.57\times 10^7\:beats$

### Part c

For item letter c), the answer is limited by 72.0, which is 3 significant figures. The answer is $7.57\times 10^7\:beats$.