A man travels by a car to his office at $60 \,km / h$ and returns home along the same route at $20 \,km / h .$ Find the average speed of his whole journey. (in $km/h$)
$40$
$50$
$30$
$25$
The average marks of a student in four subjects is $75 .$ If the student obtained $80$ marks in the $5^{\text {th }}$ subject then the new average is?
The average of $X_{1}, X_{2}$ and $X_{3}$ is $14 .$ Twice the sum of $X_{2}$ and $X_{3}$ is $30 .$ What is the value of $X_{1} ?$
The average of $30$ numbers is $15 .$ The average of the first $18$ numbers is $10$ and that of the next $11$ numbers is $20 .$ The last number is
There were $35$ students in a hostel. If the number of students is increased by $7,$ the expenditure on food increase by $Rs. \,42$ per $day$ while the average expenditure of students is reduced by $Rs.\, 1.$ What was the initial expenditure on food per day? (in $Rs.$)
Find the average of all the numbers between $6$ and $34$ which are divisible by $5$