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

The average speed of a train in the onward journey is $25\%$ less than that of the return journey. The train halts for one hour on reaching the destination. The total time taken for the complete to and fro journey is $17\, \text{hours}$,covering a distance of $800\, \text{km}$ (one way). The speed of the train in the onward journey is (in $\text{km/h}$):

What is the average of all numbers between $100$ and $200$ which are divisible by $13$ (in $.5$)?

The average of a batsman after $25$ innings was $56$ runs per innings. If after the $26^{th}$ inning his average increased by $2$ runs,then find his score in the $26^{th}$ inning?

The average marks of $120$ students are $35.$ If the average of passed students was $39$ and failed students was $15,$ then find the number of students who have passed.

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