Q10 of 176 Page 20

The ratio of the sum of the first three terms is to that of the first 6 terms of a G.P. is 125 : 152. Find the common ratio.

Sum of GP for n terms =


Sum of GP of 3 terms = 125


⇒


⇒ …(1)


Sum of GP of 6 terms = 152


⇒


⇒ …(2)


Dividing 1 by 2 we get


⇒


⇒


⇒


⇒ 125r3 + 125 = 152


⇒


⇒


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