What is the average of all multiples of $10$ from $2$ to $198$?
$ a=10,l=190$ $ s=\dfrac{n(a+l)}{2}=\dfrac{19\times (200)}{2}=1900$ Average $=\dfrac{1900}{19}=100$ Ans. is 100
Average in case of A.P. series average = (first + last) / 2 =(190+10)/2 = 100