In the first $30$ overs of a cricket match, the run rate was $5.2 \,runs/over.$ What is the required run rate in the remaining $20$ overs to reach the target of $280$ runs?

The average of a collection of $20$ measurements was calculated to be $56\, cm .$ But later, it was found that a mistake had occurred in one of the measurements which was recorded as $64 \,cm ,$ but should have been $61 \,cm$. The correct average must be? (in $cm$)

The average of the price per $kg$ of rice at $10$ different places was $Rs.\, 4.85.$ After a week, the price per $kg.$ was increased by $20$ paise at $3$ places and decreased by $10$ paise at one place. The new average of price per $kg$ is in $Rs.$

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 $years$)

Five years ago the average age of husband and wife was $23\, years.$ Today the average age of husband, wife and child is $20 \,years.$ How old is child in $years$ ?