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IMPORTANT FORMULAE, , Ls, , , , - Ray tet ky, Menz= 2+Rt-4%, n, , Pe,, , (i) Using assumed mean method, , (i) Using direct method: ¥ =, , h, Mode = / +) ———"—_, . CAS, , , , , , © Median = / +, , , , , , yd © 3 median = mode + 2 mean, F=A+ 2% gex-a, Am © Note: Symbols used above have their usual meanings,, COMMON ERRORS, Errors Corrections, , , , (i) Choosing not a suitable method to obtain the mean of, grouped data, , (i) The choice of method to be used depends on the numerical, values of x, and f,, If x, and f, are sufficiently small, the, direct method is an appropriate choice. If x, and f, are, numerically large numbers, choose the assumed mean, method., , , , (ii) Interpreting incorrectly that mode of a given data is, always less than the mean of that data,, , (ii) For a given data, mode may be equal, more than or less, than the mean of that data., , , , (iii) Interpreting incorrectly that mode can be calculated for, , (iii) The mode can also be calculated for grouped data with, , , , grouped data of equal size onl, , unequal class sizes.