The following back-to-back stem-and-leaf diagram represents the monthly salaries, in dollars, of 27 employees at each of two companies, A and B.

(a) Find the median and the interquartile range of the monthly salaries of employees in company A. [3]

The lower quartile, median and upper quartile for company B are $2600, $2690 and $2780 respectively.

(b) Draw two box-and-whisker plots in a single diagram to represent the information for the salaries of employees at companies A and B. [3]

(c) Comment on whether the mean would be a more appropriate measure than the median for comparing the given information for the two companies. [1]