If the mean of $5$ observation $x, x+2, x+4, x+6$ and $x+8$ is $11,$ then the mean of the last three observations is

In an examination average marks obtained by the girls of a class is $85$ and the average marks obtained by the boys of the same class is $87 .$ If the girls and boys are in the ratio $4: 5,$ average marks of the whole class $(approx.)$ is closest to

The average salary of the entire staff in an office is $Rs.\, 500$ per day. The average salary of officers is $Rs.\, 750$ and that of non-officers is $Rs. \,$ $250 .$ If the number of officers is $15,$ then find the number of nonofficers in the office?

The sum of three numbers is $98 .$ If the ratio between first and second be $2: 3$ and between second and third be $5: 8,$ then the second number 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 three consecutive odd numbers is $12$ more than one-third of the first of these numbers. What is the last of the three numbers ?