15, 30, 60, 120 ...... are in G.P. (Geometric Progression). (a) Find the nth term of this G.P. in terms of n. (b) How many terms of the above G.P. will give the sum 945 ?

Question

KnowledgeBoat · Accepted Answer

Given, G.P. : 15, 30, 60, 120 ...... First term (a) = 15 Common ratio (r) = = 2 (a) nth term of G.P. = arn = 15 x 2n Hence, nth term of the given G.P. is 15 x 2n (b) Let sum of n terms of G.P. is 945. By formula, Sum of n terms of G.P. = Substituting values we get : Hence, sum of 6 terms of G.P. = 945.

Mathematics

15, 30, 60, 120 …… are in G.P. (Geometric Progression).
(a) Find the nth term of this G.P. in terms of n.
(b) How many terms of the above G.P. will give the sum 945 ?

AP GP

ICSE 2024

Related Questions

In the given diagram, O is the centre of the circle. PR and PT are two tangents drawn from the external point P and touching the circle at Q and S respectively. MN is a diameter of the circle. Given ∠PQM = 42° and ∠PSM = 25°.
Find :
(a) ∠OQM
(b) ∠QNS
(c) ∠QOS
(d) ∠QMS