## anonymous one year ago The typical healthy resting heart rate in adults is 60–80 beats per minute. If you live 80 years, how many times will your heart beat?

1. mathstudent55

Ok. This is just a long multiplication. How many minutes in an hour?

2. anonymous

60

3. mathstudent55

How many hours in a day?

4. anonymous

24

5. mathstudent55

How many days in year?

6. mathstudent55

365.25

7. mathstudent55

$$80 ~years \times \dfrac{365.25~days}{year} \times \dfrac{24~hours}{day} \times \dfrac{60~minutes}{hour} \times \dfrac{60~beats}{minute}$$

8. anonymous

I got 252,460,800

9. mathstudent55

Multiply it out with 60 at the end as written above. Then do it also with 80 at the end. Then you can answer the range is from _____ to _____. Alternatively, you can calculate it once with 70 at the end.

10. mathstudent55

I get 2,524,608,000

11. anonymous

I must of did something wrong

12. mathstudent55

Your result is 10 times smaller than it would be. Maybe you entered one of the 60's as just 6.

13. mathstudent55

60 beats per minute: 2,524,608,000 80 beats per minute: 3,366,144,000 You can answer approx. 2.5 billion to 3.4 billion Using the average, 70 beats per minute: 2,945,376,000 Approx. 2.9 billion

14. anonymous

So how do i put that into one of these answers because these are the choices a)3 $10^{6}$ b)3 $10^{15}$ c)3 $10^{12}$ d)3 $10^{9}$

15. anonymous

@mathstudent55

16. mathstudent55

Ok. Now you need the average value as a number in scientific notation.

17. mathstudent55

We get an average value of 2,945,376,000. You can round this off to 3,000,000,000 (3 billion).

18. mathstudent55

3,000,000,000 = 3 * 1,000,000,000

19. mathstudent55

1 = 10^0 10 = 10^1 100 = 10^2 1000 = 10^3 10,000 = 10^4 etc. 1,000,000,000 = 10^9

20. mathstudent55

3,000,000,000 = 3 * 1,000,000,000 = 3 * 10^9

21. anonymous

So is it D

22. mathstudent55

yes

23. anonymous

Yay!!!!

24. anonymous

Thank you

25. mathstudent55

yw