math
posted by Jasen on .
A rubber ball is dropped from a height of 729 feet, and at each bounce it rebounds onethird of the height from which it last fell. How far has the ball travelled by the time it strikes the ground for the 5th time?

first time: 729/3=243
second time: 243/3
third time:81/3
fourth time: 27/3
fifth time: 9/3=3ft 
distance for 1st bounce = 729
distance for 2nd bounce = 2(1/3)(729) = 2(243)
distance for 3rd bounce = 2(1/3)(243) = 2(81)
distance for 4th bounce = 2(1/3)(81) = 2(27)
distance for 5th bounce = 2(1/3)(27) = 2(9)
total distance
= 729 + 2(243+81+27+9) = 1449