Question

Find middle value of ap 6,13,20.....216

Answer 1

first total no of term
last term =a+(n-1)d
here a=6, d=7 and last term = 216
216=6+(n-1)7
216-6=(n-1)7
210=(n-1)7
30=n-1
n=31
middle term for 31 terms series is 16
a16=a+(n-1)d
..... =6+(16-1)7
........=6+15×7
.........=6+105
..….....=111 ans.