Question

The first term of a geometric sequence is 400 and the common ratio is 0.5. What

is the 5 th term of the sequence?
100
50

Answer 1

25. The approximate answer is 25.

Answer 2

25

Explanation:

The n th term of a geometric sequence is

`a_(n)` = a₁
`r^(n-1)`

where a₁ is the first term and r the common ratio

Here a₁ = 400 and r = 0.5 , thus

`a_(5)` = 400 ×
`(0.5)^(4)` = 400 × 0.0625 = 25