precalculus math help

Question

A hard rubber ball is dropped from a roof of a building that is 4 meters high. The ball rises to 40% of the height from which it fell after each bounce. What is the total vertical distance that the ball had traveled by the time it hit the ground for the 10th time? 

Answer 1

Each bounce is 80% of the previous (40% up 40% down)

First bounce is 3.2 m.

a_n = 3.2(0.8)^n-1

S₁₀ = 3.2(1 - 0.8¹⁰) / (1 - 0.8)

Calculate and add 4 m for the drop.