The average weight of $8$ sailors in a boat is increased by $1\, kg$ if one of them weighting $56\,kg$ is replaced by a new sailor. The weight of the new sailor is (in $kg$)

The average speed of a cyclist who covers first, second and third km at $20,16$ and $12\, km / hr$ respectively ( in $km / hr )$ is

In a competitive examination, the average marks obtained was $45 .$ It was later discovered that there was some error in computerization and the marks of $90$ candidates had to be changed from $80$ to $50$ , and the average came down to $40$ marks. The total number of candidates appeared in the examination is 

The average age of mother, father and son was $42\, years.$ at the time of the marriage of the son. After one year an infant was born in the family and after $6\, years$ of marriage the average age of the family is $36\, years.$ What was the age of the bride at the time of marriage in $year.$

The average earning of a mechanic for the first four days of a week is $Rs.\,18$ and for the last four days is $Rs.\,22.$ If he earns $Rs.\, 20$ on the fourth day, his average earning for the whole week is (in $Rs.$)