The average of marks of $28$ students in Mathematics was $50 .$ $8$ students left the school, then this average increased by $5 .$ What is the average of marks obtained by the students who left the school?
$50.5$
$37.5$
$42.5$
$45$
The average age of four brothers is $12 \,year.$ If the age of their mother be also included, the average is increased by $5\, year.$ The age of the mother (in $years$) is
In a $20$ over match, the required run rate to win is $7.2 .$ If the run rate is $6$ at the end of the $15^{th}$ over, the required run rate to win the match is
Find the average of the following set of scores $253,124,255,534,836,375,101,443,760$
The average age of $20$ boys in the class is $15.6\, years.$ Five new boys join and the new average becomes $15.56\, years.$ What is the average age of the five new boys? (in $years$)
The average of two numbers $A$ and $B$ is $20 ,$ that of $B$ and $C$ is $19$ and of $C$ and $A$ it is $21 .$ What is the value of $A ?$