# Geometric Series question? Help!?

posted by
**Sam**
.

A bouncy ball bounces to 2/3 of its height when dropped on a hard surface. Suppose the ball is dropped from 20 m.

What is the height of the ball after the 6th bounce? Answer = 1280/729 m OR 1.75 m

What is the total distance travelled by the ball after 10 bounces? 98.6 m

So, I assumed a is 20 since it's the starting point of the ball. I assumed R is 2/3 because it is the common ratio(?). I plugged it into my equation, I used this equation

Sn=a(r^n - 1)/r - 1

Sn=20(2/3^6 - 1) / (2/3) - 1 and I got the wrong answer. I think I used the wrong r value.

Thank you for your help.