Question

The $A.M$ of $10$ observations is $40$, If the sum of $6$ observations is $280$ then the mean of remaining $4$ observations is

Answer 1

Sum of $10$ observations $=n\times A.M.=10\times A.M.=10\times 40=400$
$\therefore$ Mean of remaining $4$ observations$=\frac{400-280}{4}=30$