a+(a/2)+(a/4)+(a/8)+(a/16)+................upto infinite = 40 then a will be

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12 Dec 2012 series

a+(a/2)+(a/4)+(a/8)+(a/16)+................upto infinite = 40
then a will be

OPtion

1) 20
2) 15
3) 12
4) 10
5) 9
6) 21
7) 25
8) 28
9) 18
10) none of these

Solution

a+(a/2)+(a/4)+(a/8)+(a/16)+................upto infinite
by using formula of sum of infinite terms we get 2a
so 2a = 40, a = 20

Correct Option: 1 Best Solution (0)