Question

A dollar bill is about 15.5 cm long. If seventeen trillion dollar bills were laid end to end around the Earth's equator, how many times would they encircle the planet? Take the radius of the Earth at the equator to be about 6378 km.

Answer 1

The dollar bills would encircle earth 65753.1 times

Explanation:

We have

Length of dollar bill = 15.5 cm

Total dollar bills = 17 trillion =
`17* 10^(12)`

Thus the length of 17 trillion dollar bills equals

`15.5* 17* 10^(12)cm\\\\=263.5* 10^(12)cm\\\\=(263.5* 10^(12))/(10^(5))km\\\\=263.5* 10^(7)km`

Now taking shape of earth as a perfect sphere the circumference of earth becomes

`C=2\pi r\\\\=2* \pi * 6378km\\\\=40074.1558km`

Thus the number of times the dollar bills would encircle earth equals

`(263.5* 10^(7)km)/(40074.1558km)=65753.21times`