Question

The eight term of a geometrical progression is –7/32. Find it's common ratio if it's first term is 28.

Answer 1

$$b_8=b_1q^7$$

Given $b_1=28, b_8=-\dfrac{7}{32}$

$$-\dfrac{7}{32}=28q^7$$

$$q^7=-\dfrac{1}{128}$$

$$q=-\dfrac{1}{2}$$

The common ratio of the geometrical progression is $-\dfrac{1}{2}.$