Find Arithmetic Mean of series: 2, 2.5, 3, 3. 5, 4, 4. 5……….11
(A) 13/2
(B) 25/8
(C) 19
(D) 22/9
Answer: (A)
Explanation:
Arithmetic mean AM of the series is given by = (a1+a2+a3+…..+an)/n ……… (1)
But the given series is also an AP which sum is given by = (n/2)*(a1+an) ………..(2)
From equation (1),(2) we get,
AM=(a1+an)/2
AM=(2+11)/2=13/2