#### (a) Suppose that a person has an average heart rate of 72.0 beats/min. How many beats does he or she have in 2.0 y?

(b) In 2.00 y?

(c) In 2.000 y?

**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

For item letter a), the answer is limited by 2.0, which is 2 significant figures. The answer is .

### Part b

For item letter b), the answer is limited by 2.00, which is 3 significant figures. The answer is

### Part c

For item letter c), the answer is limited by 72.0, which is 3 significant figures. The answer is .