Question

find the sum of all the 11th terms of an AP whose middle most term is 30.

Answer 1

an = 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

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