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

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

(a) Calculate the variance

(i) by direct method, (ii) by step deviation method and compare your results with the mean deviation about the arithmetic mean.

(b) Calculate the coefficient of variation by using:

(i) The standard devitation of cost and (ii) the mean deviation of costs about the arithmetic mean, and compare the two. What is your conclusion about variation of cost?