The back-to-back stem-and-leaf diagram shows the annual salaries, in dollars, of 27 employees at each of two companies, Browns and Greens. Browns Greens (3) 9 8 4 30 6 8 (2) (7) 8 8 5 3 3 1 031 2 4 5 8 (4) (7) 9 7 6 4 2 2 032 3 6 6 7 9 (5) (6) 8 7 5 5 3 1 33 1 1 3 7 8 8 9 9 (8) (3) 4 2 234 0 2 3 5 6 9 (6) (1) 7 35 3 7 (2) Key: 6|32|7 means $32600 for Browns and $32700 for Greens. The annual salary of an employee at Browns is denoted by x thousand dollars and the annual salary of an employee at Greens is denoted by y thousand dollars. It is given that, for the 27 employees at each of the companies, Σx = 878.3, Σx² = 28616.09, Σy = 896.5, Σy² = 29815.63.

1. (a)Find the median and interquartile range for the annual salaries of employees at Browns.[3]
2. (b)Find the mean and standard deviation of the annual salaries of these 54 employees.[5]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.