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

The average weight of $3$ person is $65 \,kg$. If a fourth person having a weight of $45 \,kg$ joins the group, what is the average weight of the group ? (in $kg$)

The average of certain first consecutive natural numbers is $20.5 .$ Find their sum.

The average age of $80$ boys in a class is $15.$ The average age of a group of $15$ boys in the class is $16$ and the average age of another $25$ boys in the class is $14 .$ What is the average age of the remaining boys in the class ?

Average of ten numbers is calculated. If each number was increased by $12 \%$, then the average

The average of runs scored by a cricketer in his $99$ innings is $99.$ How many runs will he have to score in his $100^{\text {th }}$ innings so that his average of runs in $100$ innings may be $100 ?$