Brain Teasers Optical Illusions Puzzle Hunts Codes & Ciphers Mechanical Puzzles
Personal Links
Browse Teasers
Search Teasers

Bouncy Ball

Math brain teasers require computations to solve.


Puzzle ID:#230
Fun:*** (2.14)
Difficulty:*** (2.6)
Submitted By:Phyllis*****!
Corrected By:cnmne




If you drop a bouncy ball from a distance of 9 feet from the floor, the ball will continue to bounce. Assume that each time it bounces back two thirds of the distance of the previous bounce. How far will the ball travel before it stops?

Open Calculator


45 feet.

The distance can be calculated as 9 + (9)*(2/3)*(2) + (9)*(2/3)*(2/3)*(2)+..., with the 2 accounting for the upward and downward travel distance. Adding 9 to this will result in the formation of an infinite geometric series: 18*(2/3)^0 + 18*(2/3)^1 +... Factoring out the 18 will result in a series that is equal to (1/(1-(2/3))), which equals 3. Multiplying by the 18 and then subtracting the nine used to create the series will result in 54 - 9 = 45.


What Next?


See another brain teaser just like this one...

Or, just get a random brain teaser

If you become a registered user you can vote on this brain teaser, keep track of
which ones you have seen, and even make your own.


Back to Top

Online Now
8 users and 647 guests

Users In Chat
Follow Braingle!
Fold 'N Fly Paper Airplanes
Easy to follow folding instructions and videos.
Copyright © 1999-2017 | FAQ | Widgets | Links | Green | Subscribe | Contact | Privacy | Conditions | Advertise | Braingle Time: 7:30 am
Sign In Create a free account