The sum to infinity of a geometric progression is −110 − 1 10 and the first term is −18 − 1 8 . Find the common ratio of the progression.

Assessment: JAMB UTME - Mathematics - 2012 Subject: General Mathematics

Question 1 Report

The sum to infinity of a geometric progression is $- \frac{1}{10}$ and the first term is $- \frac{1}{8}$ . Find the common ratio of the progression.

- \frac{1}{4}

- \frac{1}{4}

- \frac{1}{4}

- \frac{1}{2}

Answer Details

Sr = $\frac{a}{1 - r}$
$- \frac{1}{10}$ = $\frac{1}{8} \times \frac{1}{1 - r}$
$- \frac{1}{10}$ = $\frac{1}{8 (1 - r)}$
$- \frac{1}{10}$ = $\frac{1}{8 - 8 r}$
cross multiply...
-1(8 - 8r) = -10
-8 + 8r = -10
8r = -2
r = -1/4

Read lesson note on Sets (WAEC)

Read lesson note on Sequence And Series (WAEC)

Sets

Sequence And Series

View Answer

The sum to infinity of a geometric progression is −110 − 1 10 and the first term is −18 − 1 8 . Find the common ratio of the progression.

Related Questions

Download The App On Google Playstore