Answer:
The answer is 57 29/125 feet ⇒ answer (C)
Step-by-step explanation:
∵ The ball dropped from a height 10 feet
∴ The vertical distance = 10 feet
∵ It bounces 4/5 as high as the preceding one
∴ 1st bounce = 10 × 4/5 = 8 (move down another 8)
∴ The vertical distance = 8 + 8 = 16 feet
∴ 2nd bounce = 8 × 4/5 = 6.4 (move down another 6.4)
∴ The vertical distance = 6.4 + 6.4 = 12.8 feet
∴ 3rd bounce = 6.4 × 4/5 = 5.12 (move down another 5.12)
∴ The vertical distance = 5.12 + 5.12 = 10.24 feet
∴ 4th bounce = 5.12 × 4/5 = 4.096 (move down another 4.096)
∴ The vertical distance = 4.096 + 4.096 = 8.192 feet
∵ The ball will hit the surface to make the 5th bounce
∴ The total vertical distance is :
10 + 16 + 12.8 + 10.24 + 8.192 = 57.232 = 57 29/125
Another way:
* We can use the formula of geometric sequence with
1st bounce distance (a) = 8 + 8 = 16 and ratio (r) = 4/5
and number of bounces (n) = 4 (hit the surface for its 5th bounce)
∵ [tex]S_{n}=\frac{a(1-(r^{n}))}{1-r}[/tex]
∴ [tex]S_{4}=\frac{16(1-(\frac{4}{5})^{4})}{1-\frac{4}{5}}=47\frac{29}{125}[/tex]
* Then we must to add the 10 feet
(the ball dropped from height 10 feet)
∴ The total vertical distance = 10 + 47 29/125 = 57 29/125 feet
