A tennis ball is initially dropped from a height of 180 m. After striking the ground, it rebounds (3/5)^{th} of the height from which it has fallen. The total distance that the ball travels before it comes to rest is:

**(A)** 540 m

**(B)** 600 m

**(C)** 720 m

**(D)** 900 m

**Answer:** **(C)** **Explanation:** The total distance traveled by the ball is the sum of two infinite series:

a. Series 1: the distance traveled by the ball when it’s falling down

b. Series 2: the distance traveled by the ball when it’s bouncing up

S1 = a1 / (1 – r1) and S2 = a2 / (1 – r2)

S1 = 180 / (1 – 3/5) and S2 = (180 * 3/5) / (1 – 3/5)

S1 = 180 / (2/5) and S2 = 108 / (2/5)

S1 = 180 * 5/2 and S2 = 108 * 5/2

S1 = 450 and S2 = 270

Therefore, S = S1+S2 = 720 m.

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