If the arithmetic mean of the numbers x1,x2,x3,…,xk is x¯ , then the arithmetic mean of the numbers
ax1+b,ax2+b,ax3+b..........axn+b,
where a,b are two constants, would be
x
nax+nb
ax
ax+b
Required mean is ax1+b+ax2+b+⋯+axn+bn
=ax1+x2+⋯+xnn+b=ax¯+b ∵x1+x2+⋯+xnn=x¯