Question

If average of 'n' terms of a series is one more than number of terms..then find the average of 13th and 14th terms of this series?​

Answer 1

Answer:

27

Step-by-step explanation:

(a1+a2+....+an)/n=1+n

a1+a2+...an=n(1+n)

(a1+a2+....+an)/2=$\frac{n(n+1)}{2}$= sum of n natural numbers

∴$\frac{a1}{2},\frac{a2}{2},...,\frac{an}{2}$ are consecutive natural numbers

∴a1=2,a2=4....,an=2n

Hence a13=26 and a14=28

average of26 and 28 is 27