Math Formulae: Averages

Some need to remember Average Formulae:

1. Average is the arithmetic mean of given data.
   
   
2. Average lies between highest and lowest values in th given data.
   
   
3. If X is added to all the values in the given set of data, then average of the data increases by X.
   
   
4. If X is subtracted from all the values in the given set of data, then average of the data decreases by X.
   
   
5. If X is multiplied to all the values in the given data, then new average X times the old average.
   
   
6. If all the values in the given data is divided by X, then new average of the data is old average divided by X, provided X is not 0.
   
   
7. If given set of data is in arithmetic series,
   then, if number of values in data is odd, then average is middle value
   and, if number of values is even, then average is mean of mid two values,
   provided that data is arranged in increasing or deceasing order.
   For Example: average of 1, 3, 5, 7, 9 is 5,
   and that of 1, 3, 5, 7 is 8
   
   
8. Weighted Average:

   Aw =	(k1.A1 + k2.A2 + ..... + kn.An)
   	(k1 + k2 + ...... + kn)

   where, k₁, k₂, .... , k_n are weights associated with A₁, A₂, ... ,A_n respectively.

These formulae can be found in tools section of Tricky Maths App.