Question

The distribution of number of ball bearings used in machines of a factory is given below. Calculate the mean deviation and coefficient of mean deviation of number of ball bearings per machine.

No. of ball bearings	2	4	6	8	10	12	14	16
No. of machines	2	2	4	5	3	2	1	1

Answer 1

Mean:
x̄ = \( \frac{Σfx}{n}=\frac{160}{20}\) = 8 ball bearing

Mean deviation of numbers of ball bearing:

MD = \(\frac{Σf|x−\bar x|}{n}\)

= \(\frac{56}{20}\) = 28 ball bearing

Coefficient Mean deviation of ball bearing:

Coefficient of mean deviation = \(\frac{MD}{\bar x}\)

= \(\frac{2.8}{8}\) = 0.35