Question

Find the sum of first 11 terms of AP whose middle term is 30

Answer 1

n = 11  

(a1+a11)/2 = 30

(a1+a11)= 60

Sum of AP = n(a1+a11)/2

                 = 11*60/2

                 = 11*30

                 = 330

SUM OF THE 11TH TERMS IS 330