Find the mean, median, and mode of the following set of data: 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5.
The average salary paid to graduates in three companies is: £7000, £6000, and £9000 per annum respectively. If the respective number of graduates in these companies is 5, 12, and 3, fi nd the mean salary paid to the 20 graduates.