The average of a non-zero number and its square is $5$ times the number. The number is

The average age of a husband and wife, who were married $7 \,years$ ago, was $25\, years$ at the time of their marriage, Now, the average age of the family, including husband, wife and a child, born during the interval, is $22\, years.$ What is the present age of the child in $year$ ?

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 $87 \,kg.$ The correct average weight is (in $kg.$)

Find average of all prime numbers between $60$ and $90.$

What will be the average of even numbers between $11$ to $63 ?$

A library has an average of $510$ $visitors$ on Sundays and $240$ on other days. The average number of visitors per day in a month of $30 \,days$ beginning with a Sunday is