The average of husband, wife and their child $3\, years$ ago was $27\, years$ and that of wife and the child $5\, years$ ago was $20\, years.$ The present age of the husband is (in $years$)

In an entrance examination, Ritu scored $56$ percent marks, Smita scored $92$ percent marks and Rina scored $634$ marks. The maximum marks of the examination is $875 .$ What is the average marks scored by all the three girls together ?

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

A student finds the average of $10,2$ digit numbers. If the digits of one of the number is interchanged, the average increases by $3.6 .$ The difference between the digits of the $2 -$digit numbers is

The average salary of the entire staff in an office is $Rs.\, 500$ per day. The average salary of officers is $Rs.\, 750$ and that of non-officers is $Rs. \,$ $250 .$ If the number of officers is $15,$ then find the number of nonofficers in the office?

A batsman in his $17^{th}$ innings, makes a score of $85$ runs, and there by, increases his average by $3$ runs. What is his average after the $17^{th}$ innings ? He had never been $'not out'.$