Question:
Choose the correct answer in each of the following questions:
The common difference of the AP $\frac{1}{3}, \frac{1-3 b}{3}, \frac{1-6 b}{3}, \ldots$ is
(a) $\frac{1}{3}$
(b) $\frac{-1}{3}$
(c) $b$
(d) $-b$
Solution:
The given AP is $\frac{1}{3}, \frac{1-3 b}{3}, \frac{1-6 b}{3}, \ldots$
$\therefore$ Common difference, $d=\frac{1-3 b}{3}-\frac{1}{3}=\frac{1-3 b-1}{3}=\frac{-3 b}{3}=-b$
Hence, the correct answer is option D.