Can someone help me solve this question?

Question

suppose the intial height from which the rubber ball drops is 100in. The rebound heights to the nearest inch are 80, 64, 51, 41
a) what is the rebound ratio for this ball?
b) what is the height of the tenth rebound?
c) after how many bounces will the ball rebound less then 1in? less then 0.1in?

Answer 1

a. 80/100 = 4/5
b. 100*(.8^10) = 10.737 or 11 (to the nearest whole inch)
c. 1 = 100 * (.8^n)
.01 = .8^n
n is between 20 and 21, so 21 bounces
.1 = 100*(.8^n)
.001 = .8^n
n is between 30 and 31, so 31 bounces