The average of n numbers ${\mathrm{x}}_1,{\mathrm{x}}_2,{\mathrm{x}}_3,\dots ,{\mathrm{x}}_{\mathrm{n}}$ is M. If $x_n$ is replaced by x', then new average is

• A

  $\mathrm{M}-{\mathrm{x}}_{\mathrm{n}}+{\mathrm{x}}^{\mathrm{\prime }}$

• B

  $\frac{\mathrm{nM}-{\mathrm{x}}_{\mathrm{n}}+{\mathrm{x}}^{\mathrm{\prime }}}{\mathrm{n}}$

• C

  $\frac{(\mathrm{n}-1)\mathrm{M}+{\mathrm{x}}^{\mathrm{\prime }}}{\mathrm{n}}$

• D

  $\frac{\mathrm{M}-{\mathrm{x}}_{\mathrm{n}}+{\mathrm{x}}^{\mathrm{\prime }}}{\mathrm{n}}$