3. The table shows the weekly turnover of a small shop over a period during Spring and Summer. Sales ($) 0 - 99 100 - 199 200 - 299 300 - 399 Number of weeks 2 9 15 7 (a) Find the mean weekly sales. . . . . . . . . . . . . (b) Find the sample standard deviation of the sales. . . . . . . . . (c) Construct a cumulative frequency table and draw the cumulative frequency curve. (d) Find the median weekly sales from your graph. . . . . . . . . . . . . . . . . . (e) Find the quartiles and the inter-quartile range of the sales from your graph