The average salary per head of all the workers in a workshop is $Rs.\,850.$ If the average salary per head of $7$ technicians is $Rs.\, 1000$ and the average salary per head of the rest is $Rs.\, 780,$ find out the total number of workers in the workshop.

On $24^{\text {th }}$ May, 2008 the maximum temperature of Delhi, Kollkata and Mumbai were recorded as $35^{\circ} C$, $33^{\circ}$ and $34^{\circ} C$ respectively. What was the maximum temperature of Chennai so that the average maximum temperature of those cities would be $35^{\circ} C$ (in $^{\circ} C$ )

Visitors to a show were charged $Rs.\, 15$ each on the first day, $Rs.\, 7.50$ on the second day, $Rs.\, 2.50$ on the third day and total attendance on three days were in the ratio $2: 5: 13$ respectively. The average charge per person for the entire three days is (in $Rs.$)

A man whose bowling average is $12.4,$ takes $5$ wickets for $26$ runs and, thereby, decreases his average by $0.4$ The number of wickets, taken by him, before his last match is

The average marks obtained by $180$ students in an examination is $50 .$ If the average marks of passed students is $40 .$ Then what is the number of students who failed the examination ?

The sum of three consecutive odd numbers is $38$ more than the average of these numbers. What is the first of these numbers