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Suppose a ball is dropped from a height of 6 ft. It bounces back up. But each time it bounces, it reaches only 7/10 of its previous height. What is the total distance the ball bounces (distance falling and going up) through the 5th bounce?

Respuesta :

1st bounce 7/10 * 6 = 42/10 = 21/5
2nd bounce 7/10 * 21/5 = 147/50
3rd bounce 7/10 * 147/50 = 1029/500
4th bounce 7/10 * 1029/500 = 7203 / 5000
5th bounce  7/10 * 7203/5000 = 50421/50000 = 1.00842

Answer: 16.6386 ft.

Step-by-step explanation:

Given: A a ball is dropped from a height of 6 ft.

Each time it bounces, it reaches only 7/10 of its previous height.

i.e. after 1st bounce the height reached by the ball is given by :-

 [tex]6\times\dfrac{7}{10}[/tex]

After 2nd bounce the height reached by the ball is given by :-

[tex]6\times\dfrac{7}{10}\times\dfrac{7}{10}=6\times(\dfrac{7}{10})^2[/tex]

Thus, it is following a geometric progression with common ratio (r)=7/10=0.7 and the first term = 6

The sum of geometric progression  of first n terms is given by ;-

[tex]\dfrac{a(1-r^n)}{1-r}[/tex]

Now, the  total distance the ball bounces (distance falling and going up) through the 5th bounce is given by:-

[tex]\dfrac{6(1-(0.7)^5)}{1-0.7}=16.6386[/tex]