Averages and Mixtures - Formulae, Shortcuts

Formulae:

1.       Average = sum of quantities/number of quantities

2.       Sum = avg * no. of quantities

3.       If the numbers are in A.P. (Arithmetic Progression), then the avg of numbers is given by

Avg = sum/n =[ (n/2)(a+l)]/n

                = (a+l)/2

Where  n – no. of quantities

                a – first term or value

                l – last term or value

4.       Weighted Average:

Section1:

                No. of quantities: m

                Avg of section1: p

Section2:

                No. of quantities: n

                Avg of section1: q

Avg of section1 and section2 = (m*p + n*q)/(m +n)

Points to remember/Shortcuts

1.       Average lies between minimum and maximum values.

a.       Avg > minimum value

b.      Avg < maximum value

2.       If every quantity is increased/decreased by ‘k’ value, then the avg also get increased/decreased by the same ‘k’ value.