The average weight of a group of $20$ boys was calculated to be $89.4 kg$ and it was later discovered that one weight was misread as $78 kg$ instead of the correct one of $87 kg$. The correct average weight is in $kg$

The average of $50$ numbers is $38 .$ If two numbers, namely, $45$ and $55$ are discarded, what is the average of the remaining numbers ?

The average weight of $36$ students is $50 \,kg$. It was found later that the figure of $37 \,kg$ was misread as $73 \,kg.$ What is the correct average? (in $kg$)

$5$ members of a team are weighed consecutively and their average weight calculated after each member is weighed. If the average weight increases by one kg each time, how much heavier is the last player than the first one? (in $kg$)

The average weight of $3 \operatorname{men} A, B$ and $C$ is $84\, kg.$ Another man $D$ joins the group and the average now becomes $80 \,kg .$ If another man $E ,$ whose weight is $3 \,kg$ more than that of $D ,$ replaces $A,$ then the average weight of $B, C, D$ and $E$ becomes $79 \,kg .$ The weight of $A$ is (in $kg$)