The average of $13$ results is $60 .$ If the average of first $7$ results is $59$ and that of last $7$ results is $61,$ what will be the seventh result $?$

In a coconut grove, $(x+2)$ trees yield $60$ $nuts$ per $year,$ $x$ trees yield $120\, nuts$ per $ year,$ and $(x-2)$ trees yield $180 \,nuts$ per $year$. If the average yield per $year$ per tree be $100,$ find the value of $x .$

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 $4 \,?$ 

In a school with $600$ students, the average age of the boys is $12$ $years$ and that of the girls is $11\, years.$ If the average age of the school is $11 \,years$ and $9 \,months,$ then the number of girls in the school is

The average temperature from Monday to Thursday is $48^{\circ} C$ and from Tuesday to Friday, the average temperature is $52^{\circ} C$. If the temperature on Monday is $42^{\circ} C$, what was it on Friday in $^{\circ} C$?

The average of $100$ observations was calculated as $35.$ It was found later, that one of the observations was misread as $83$ instead of $53 .$ The correct average is