Quant Question Of The Day: 142
Algebra
Sum of an infinite G.P. is 162 and sum of first n terms of the same G.P. is 160. How many rational values are possible for the common ratio?
1. 2
2. 3
3. 5
4. Infinite
Using the formulas for sum of infinite G.P. and sum of n terms of G.P. we get r n = 1/81. So, the possibilities are (1/81)1 , (1/9)2 , (1/3)4 , (-1/9)2 , (-1/3)4. So 5 values of r are possible.
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