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The number of telephone calls received in 245 successive one minute intervals at an exchange is given below in the following frequency distribution.

Number of calls	0	1	2	3	4	5	6	7
Frequency	14	21	25	43	51	40	39	12

[NDA I 2014]

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Question : 93 of 100

Marks: +1, -0

What is the mean of the distribution ?

3.76
3.84
3.96
4.05

Solution:

\text{Mean}= \frac{14 \times 0 + 21 \times 1 + 25 \times 2 + 43 \times 3 + 51 \times 4 + 40 \times 5 + 39 \times 6 + 12 \times 7}{245}

= \frac{922}{245} = 3.76

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