# The Number of Telephone Calls Received at an Exchange per Interval for 250 Successive One Minute Intervals Are Given in the Following Frequency Table: - Mathematics

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.

#### Solution

Let be assumed mean (A) = 3

 No. of calls (x1) No. of intervals (f1) u1 = x1 - A (A = 3) f1u1 0 15 -3 -45 1 24 -2 -47 2 29 -1 -39 3 46 0 0 4 54 1 54 5 43 2 86 6 39 3 47 N = 250 sumf_1u_1=135

Mean number of cells =A+(sumf_1u_1)/N

=3+135/250

=(750 + 135)/250

=885/250

= 3.54

Is there an error in this question or solution?

#### APPEARS IN

RD Sharma Class 10 Maths
Chapter 15 Statistics
Exercise 15.2 | Q 1 | Page 13