Posted by Marisol on .
A ball has a 75% rebound ratio. When you drop it from a height of 16 ft, it bounces and bounces...
When it strikes the ground for the second time, the ball has traveled a total of 28 ft in a downward direction. How far downward has the ball traveled when it strikes the ground for the 17th time?

math 
MathMate,
T(1)=16
T(2)=12
T(3)=9
...
T(n)=16(3/4)^(n1)
It is a geometric progression (GP) with a ratio of 3/4.
The sum to n terms of a GP is:
S(n)=16(1(3/4)^n)/(1(3/4))
Substitute n=17 in the above formula to get S(17), the total downward distance.