The average age of Seema, Sapna, Asha, Kavita and Atrye is $40 \,years.$ The average age of Seema and Sapna is $35 \,years$ and the average age of Asha and Kavita is $42 \,years.$ The age of Atrye is?

In a family, the average age of a father and a mother is $35\, years.$ The average age of the father, mother and their only son is $27\, years.$ What is the age of the son ? (in $years$)

The average marks obtained by $180$ students in an examination is $50 .$ If the average marks of passed students is $40 .$ Then what is the number of students who failed the examination ?

The average age of board of directors of a company, having $10$ directors was $48$ years. Coincidentally when a director aged $53$ resigned from the board of directors, another director died on the same day. So a new director joined the board of directors aged $34.$ Next year in the same month the average age of all the $9$ directors was found to be $46 \,years.$ The age of the late (i.e., dead) director at the time of his death was (in $years$)

A cricketer whose bowling average is $12.4$ runs per wicket takes $5$ wickets for $26$ runs and thereby decreases his average by $0.4$ The number of wickets taken by him till the last match was