charlier's accuracy check

Shirley,

When we calculate the arithmetic mean in case of the frequency distribution series using short cut method or step deviation method, we can check the accuracy of solution using the formula that Charlier introduced. Formula is as follows:

i) For the short cut method : $\sum \left|f\left(dx + 1\right)\right| = \sum fdx + \sum f$
ii) For the step- deviation method : $\sum \left|f\left(d\text{'} + 1\right)\right| = \sum fd\text{'} + \sum f$

If left hand side of the equation is equal to the right hand side of equation, then we can say that the solution is correct.