Indian Institute of Foreign Trade 2016 Solved Paper

Question : 2 of 123

Marks: +1, -0

A child, playing at the balcony of his multi-storied apartment, drops a ball from a height of 350 m. Each time the ball rebounds, it rises

4/5

th of the height it has fallen through. The total distance travelled by the ball before it comes to rest is

2530 m
2800 m
3150 m
3500 m

Validate

Solution:

( 350 × { 4 }/ { 5 } )

andapplying the formula for infinite G.P.
Here,

a = 280 , r = { 4 }/ { 5 }

⇒ { a } { 1 - 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.

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