In a business hourse, the weekly salaries of 30 employees are given below :

Find the arithmetic mean of the bonus of the employees.

Explanation

We have to prepare , firstly the frequency distribution table . In this table, the class intervals are 61-75, 76-90, 91-105, …………… etc. The frequency of these intervals are `f_(1), f_(2), f_(3)………… etc` , and the rate of bonus are `y_(1), y_(2), y_(3), `..... etc. Then the arithmetic mean of bonus , `bary=(sum y_(i)f_(i))/(sum f)`
To find the arithmetic mean, let us prepare the frequency table :

In the case of the variable , let us assume 100 as the origin and class length 254 as the unit then `u=(y-100)/(25)` and `bary=100+25.baru`
Here , `baru=(sum u. f)/(sum f)=(24)/(30)=4/5`
`therefore bary=100+25*(4)/(5)=Rs. (100+20)=Rs. 120`
`therefore ` the average of bonus is Rs. 120.