Question

80 coins be placed in a straight line exactly 10 metre apart how far must a person travel to bring them one by one to a basket placed in 10 metres behind the first coin​ ​

Answer 1

Answer:

a)64800

Explanation:

Basket is 10 feet behind first coin.To take first coin a person has to travel 20ft(10+10) to and fro.Similarly,to collect second coin he has to travel 40ft (20+20) to & fro.This forms an A.P series.T0 collect last coin he has to travel 1600ft(800+800)

(10+10)+(20+20)+..............+(800+800)

=20+40+60+80+......+1600

Sum of n terns in A.P is n(a1+an)/2.

hence Sum of first 80 terms =80(20+1600)/2

=64800

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