Q) Following is the daily expenditure on lunch by 30 employees of a company:

Find the mean daily expenditure of the employees.

Ans: We can solve this question by 2 methods: (you can choose any one method whichever you like):

I. Direct Method:

let’s re-arrange the data with midpoint of each class, frequency, and multiply midpoint with frequency:

Next, mean of grouped data is given by: 

Mean of grouped data =

Therefore, Mean expenditure = = 148

Hence, the mean expenditure of the given data is 148.

II. Assumed Mean Method:

We take center class as a = 150

Next, let’s re-arrange the data with midpoint of each class, frequency, take deviation, and multiply frequency with midpoint:

We know that, mean of grouped data is given by:

Mean of grouped data = a +

Therefore, Mean expenditure = 150 + = 148

Hence, the mean expenditure of the given data is 148.

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