monthly consumption of electricity of some consumers is given below as a distribution. Find the missing frequency(x), if mode is given to be 200 units.

Monthly cosumption(in units ) 90-120 120-150 150-180 180-210 210-240

Number of consumers 20 15 X 75 30



We have, mode = 200 unitsSo, modal class = 180 - 210lower limit of modal class, l = 180frequency of modal class, f1 = 75frequency of class preceeding modal class, f0 = xfrequency of class succeeding modal class, f2 = 30class size, h = 30Now, mode = l + f1 - f02f1 - f0 - f2 × h  200 = 180 + 75 - x150 - x - 30 × 30   20 = 75 - x120 - x × 30   2 120 - x = 3 75 - x   240 - 2x = 225 - 240   x = -15

Now, missing frequency = -15But frequency can not be negative, so kindly recheck the data given in your question. 

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the missing frequency x=-15 but as frequency cannot be negative x=15

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