The average of $11$ numbers is $10.9$ If the average of the first six is $10.5$ and the average of last six is $11.4,$ find the middle (sixth) number.
$11$
$10.6$
$11.5$
$10.45$
The average weight of $15$ oarsmen in a boat is increased by $1.6\, kg$ when one of the crew, who weighs $42\, kg$ is replaced by a new man. Find the weight of the new man (in $kg$)
The average age of $8$ men is increased by $2\, years.$ When $2$ of them, whose ages are $20\, years$ and $24 \,years$ respectively, are replaced by $2$ women. What is the average age of these two women ? (in $years$)
The average weight of $4$ men $A, B, C$ and $D,$ is $67\, kg.$ The $5^{th}$ man $E$ is included and the average weight decreases by $2 \,kg$. A is replaced by $F.$ The weight of $F$ is $4 \,kg$ more than $E$. Average weight deereases because of the replacement of $A$ and now the average weight is $64\, kg.$ Find the weight of $A ?$
The average of the boys in a class is $16\, years$ and that of girls is $15\, years.$ The average age for the whole class is
After replacing an old member by a new member, it was found that the average age of five members of a club is the same assit was $3 \,year$ ago. The difference between the ages of the replaced and the new member is ? (in $year$)