Indian Institute of Foreign Trade 2016 Solved Paper

(c) Taking the first term (a) to be 280(350×

4

5

) andapplying the formula for infinite G.P.
Here, a=280,r=

4

5

⇒a1−r=

280

1− 4 5

=1400
Now since the ball travels any distance twice, once up and next down we take 2(1400) = 2800.
Hence, total distance travelled by the ball before it comes to rest = 2800 + 350 = 3150 meter.