1.

Find the 4th term from the end of the G.P. 2/27, 2/9, 2/3, …., 162.

Answer»

The nth term from the end is given by:

an = l (1/r)n-1 where, l is the last term, r is the common ratio, n is the nth term

Given: last term, l = 162

r = t2/t1 = (2/9) / (2/27)

= 2/9 × 27/2

= 3

n = 4

So, an = l (1/r)n-1

a4 = 162 (1/3)4-1

= 162 (1/3)3

= 162 × 1/27

= 6

∴ 4th term from last is 6.



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