The average of the first $100$ positive integers is

A man whose bowling average is $12.4,$ takes $5$ wickets for $26$ runs and, thereby, decreases his average by $0.4$ The number of wickets, taken by him, before his last match is

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

A batsman, in his $12^{th}$ innings, makes a score of $63$ runs and thereby increases his average score by $2.$ The average of his score after $12^{th}$ innings is

The average marks of a group of $20$ students on a test is reduced by $4$ when the topper who scored $90$ marks is replaced of a new students. Find the marks of the new student.

The arithmetie mean of the scores of a group of students in a test was $52 .$ The brightest $20 \%$ of them secured a mean score of $80$ and the dullest $25 \%$ a mean score of $31.$ The mean score of remaining $55 \%$ is