Question

Find the middle term of the A.P $7,13,19,....241$.

Answer 1

$l=a+(n-1)d$

where

$l=$ last term

$a=$ first term

$n=$no of terms

$d=$common difference

$241=7+(n-1)6$

$241-7=6n-6$

$241-1=6n$

$240/6=n$

$n=40$

$t_{20}=7+(20-1)6$

$t_{20}=7+114$

$t_{20}=121$

$t_{21}=121+6$

$t_{21}=127$