Question

How many terms are there in the sequence $15\frac{1}{2},13,......-47$?

• A. $27$
• B. $26$
• C. $28$
• D. None

Answer 1

Answer: (B)

$26$

Given series is $15\frac{1}{2},13,.....,-47$

$a_n=a+(n-1)d$
$\therefore -47=\frac{31}{2}+(n-1)\left(\frac{-5}{2}\right)$
$-47=\frac{31}{2}-\frac{5n}{2}+\frac{5}{2}$
$-47=18-\frac{5n}{2}$
$\frac{5n}{2}=65$
$\therefore n=\frac{65\times 2}{5}=26$
Hence number of terms are $26$