Of the $3$ members whose average is $22 .$ What is the first number ?
$16$
$20$
$22$
$18$
The average of $20$ numbers is $30$ and that of other $30$ numbers is $50 .$ What is the average of all the numbers.
The average income of $A$ for $15$ days is $Rs.\,70.$ The average for first five days is $Rs.\, 60$ and that for the last nine days is $Rs.\,80.$ A's income for the sixth day is (in $Rs.\,$ )
Out of $30$ teachers of a school, a teacher of age $60$ $years$ retired. In his place another teacher of age $30$ $years$ was appointed. As a result, the mean age of the teachers will
The average weight of $24$ students is $35\, kgs.$ If the weight of teacher is added the average increased by $400\, gms$. What is the weight of the teacher? (in $kg$)
The average of the squares of of first ten natural numbers is