Let a business-man have sold rice of 15 quintal , 19 quintal and 20 quintal in three consecutive months. Then how many quintal of rice had he sold per month as a average ?

Explanation

Here , let x is the variable of quantity of rice . Then the three values of x and `x_(1), x_(2) and x_(3)` the unit being quintal each.
Then the arithemetic mean of these values of x is
`bar x=(x_(1)+x_(2)+x_(3))/(3)=(15+19+20)/(20)` quintals `=(54)/(3)` quintals =18 quintals
Hence , he had sold 18 quintals of rice per month.