The number of telephone calls received at an exchange per interval for 250 successive one-minute intervals are given in the following frequency table:
No. of calls ($x$): 0 1 2 3 4 5 6
No. of intervals ($f$): 15 24 29 46 54 43 39
Compute the mean number of calls per interval.

Given:

The number of telephone calls received at an exchange per interval for 250 successive one-minute intervals.

To do:

We have to compute the mean number of calls per interval.

Solution:

Let the assumed mean $A=4$

We know that,

Mean $=A+\frac{\sum{f_id_i}}{\sum{f_i}}$

Therefore,

Mean $=4+\frac{-115}{250}$

$=4+\frac{-23}{50}$

$=\frac{4(50)-23}{50}$

$=\frac{177}{50}$

$=3.54$

The mean number of calls per interval is $3.54$.

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Updated on: 10-Oct-2022

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No. of calls ($x$):	0	1	2	3	4	5	6
No. of intervals ($f$):	15	24	29	46	54	43	39

The number of telephone calls received at an exchange per interval for 250 successive one-minute intervals are given in the following frequency table:No. of calls ($x$):0123456No. of intervals ($f$):15242946544339Compute the mean number of calls per interval.