Discussion

Explanation:

Initial distance travelled = 180 m

Distance travelled after 1st rebound

Upward = $\frac{3}{5}$ × 180 = 108 m

Downward = 108 m

Total = 108 + 108 = 216 m

Distance travelled after 2nd rebound (upward and downward)

= $\frac{3}{5}$ × 108 × 2 = $\frac{3}{5}$ × 216 m

This gives an infinite G.P. with

a = 216 and r = $\frac{3}{5}$.

For an infinite G.P. with r <>

s = $\frac{a}{1-r}$ = $\frac{216}{1-{\displaystyle \frac{3}{5}}}$ = 540 m

Since initial distance was 180 m,

Total distance = (180 + 540) m = 720 m

Hence, option (c).

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