Question

If N₁ = 10 and N₂ =9 are the sizes where 9 and 10 are the mean of the data respectively then find the 10th number.

Answer 1

$\mu=\dfrac{Sum of all numbers}{Number sizes}$

Sum $= \mu\times N$

Sum₁ $=9\times10 =90$

Sum₂$=10\times9=90$

The 10^th number $=90-90$

$=0$