October 2024
Problem of the Month

How Tall is That?
by Kipp Johnson of Valley Catholic School, Beaverton, Oregon

In 2024, Jeff Bezos was again named the world's richest person, with a net worth of two hundred billion dollars.

In the Great Depression, lots of people took all their cash and hid it under a mattress in their home because they feared that banks were not safe.

If Jeff Bezos took his entire fortune in one dollar bills and put them in a single vertical pile under his mattress, how tall would the pile be?

Give your answer to the nearest ten miles.

Scroll down for a hint...















The thickness of a dollar bill is 0.004375 inches.

Solution:

Two hundred billion dollar bills would be 13,810 miles high.

This is a dimensional analysis problem.
Take 200,000,000,000 and multiple by 0.004375 to get 875,000,000 inches.
Divide by 12 to get 72,916,666.6667 feet.
Divide by 5,280 to get 13,809.974 miles.

Correctly solved by:

1. Kamal Lohia	Holy Angel School, Hisar, Haryana, India
2. Davit Banana	Istanbul, Turkey
3. Dr. Hari Kishan	D.N. College, Meerut, Uttar Pradesh, India
4. Ryan Hall	Parkview Elementary, Chico, California, USA
5. K. Sengupta	Calcutta, India
6. Colin (Yowie) Bowey	Beechworth, Victoria, Australia
7. Mrs. Painter's 2nd block Honors Precalculus Class	Broome High School, Spartanburg, South Carolina, USA
8. Mrs. Painter's 4th block Honors Precalculus Class	Broome High School, Spartanburg, South Carolina, USA
9. Ivy Joseph	Pune, Maharashtra, India

Send any comments or questions to: David Pleacher