The distribution of the cost of production (in rupees) of a quintal of wheat in 50 farms is as follows:

Cost (in Rs.)	Number of Farms
40–50	3
50–60	6
60–70	12
70–80	18
80–90	9
90–100	2
Total	50

(a) Calculate the variance.

(i) by direct method.

(ii) by step deviation method and compare your results with the mean deviation about the arithmatic mean.

(b) Calculate the coefficient of variation by using

(i) the standard deviation of costs and

(ii) the mean deviation of cost about the arithmatic mean and compare the two. What is your conclusion about variation of cost.