The average of $17$ numbers is $10.9 $ If the average of first nine numbers is $10.5$ and that of the last $9$ numbers is $11.4,$ the middle number is

The average of runs of a cricket player of $10$ innings was $32 .$ How many runs must he make in his next innings so as to increase his average of runs by $4 \,?$ 

A man covers $\frac{1}{3}$ of his journey by train at $80\, km / h ,$ next $\frac{1}{3}$ by $60\, km / h$ and the rest by bicycle at $30 \,km / h$. Find the average speed of the man during the whole journey. (in $km/h$)

The average weight of $45$ students in a class was calculated as $36 \,kg$. It was later found that the weight of two students in the class was wrongly calculated. The actual weight of one of the boys in the class was $32 \,kg ,$ but it was calculated as $34$ $kg ,$ and the weight of another boy in the class was $45 \,kg ,$ whereas it was calculated as $40 \,kg$. What is the actual average weight of the $45$ students in the class ? (in $kg$) (Rounded off to two-digits after decimal) 

The average age of three boys is $15$ $year.$ If the ratio of their ages is $3:5: 7,$ what is the age of the oldest boy in $year$?