NECO 2022 · Paper 1 · Q13

Sequences & series (AP, GP)

The 6th term of a Geometric Progression (G.P.) is 486. Find the common ratio if its first term is 2.

Worked solution (try it first)

The 6th term is $ar^5$ , so $2r^5 = 486$ .
Divide by 2: $r^5 = 243$ .
$243 = 3^5$ , so $r = 3$ , option D.

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