Q8 of 97 Page 199

The sum of some terms of G.P. is 316 whose first term and the common ratio are 6 and 2, respectively. Find the last term and the number of terms.

Let the sum of n terms of the G.P. be 316.


It is known that,



It is given that the first term a is 6 and common ratio r is 2.







∴ n = 6


nth term of G.P is given by -


an = arn - 1


∴ Last term of the G.P = 6th term = ar6 - 1 = (6)(2)6 = (6)(32) = 160


Thus, the last term of the G.P. is 160.


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