Find the mean of 12, 15, 7, 8 and 'x + 13', if x = 2

In a particular week, the average earning per day of a plumber from Monday to Wednesday remained Rs. 580 and that from Thursday to Saturday it was Rs. 612. If the average earning for the whole week was Rs. 675, then how much did he earn on Sunday ?

Median of the data is:

The mean of 30 observations was 15. Upon checking, it was found that two observations were wrongly taken as 2 and 5. If incorrect observations are replaced by the corrected values 7 and 11, then the corrected mean is?

The average of $39$ numbers is $17$. Each number is multiplied by $12$ and then $16$ is added to each number. Finally, each number thus formed is divided by $11$.

Determine the average of the new sets of numbers thus formed ?

The median of the given data is:

7, 5, 2, 3, 6, 9, 1

Find the average of squares of first five natural numbers.