Thursday 19 December 2013

SEQUENCE AND SERIES A3

The 1st term of a geometric progression is 3 and the 6th term is 96. Find the common ratio.

Solution

G1=3, G6=96, n=6

Gn = G1rn-1;

G6 = G1r6-1;

G6 = G1r5;

96 = 3 x r5;

96 = 3r5;
 3     3

32 = r5;  Finding the fifth root of 32,

r = 2


Hence the common ratio is 2.

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