5 At a certain resort the number of hours of sunshine, measured to the nearest hour, was recorded on each of 21 days. The results are summarised in the table.
| Hours of sunshine | 0 | \(1 - 3\) | \(4 - 6\) | \(7 - 9\) | \(10 - 15\) |
| Number of days | 0 | 6 | 9 | 4 | 2 |
The diagram shows part of a histogram to illustrate the data. The scale on the frequency density axis is 2 cm to 1 unit.
\includegraphics[max width=\textwidth, alt={}, center]{56ca7462-d061-48d3-bc5f-274d925e4e34-3_944_1778_699_148}
- (a) Calculate the frequency density of the \(1 - 3\) class.
(b) Fred wishes to draw the block for the 10 - 15 class on the same diagram. Calculate the height, in centimetres, of this block. - A cumulative frequency graph is to be drawn. Write down the coordinates of the first two points that should be plotted. You are not asked to draw the graph.
- (a) Calculate estimates of the mean and standard deviation of the number of hours of sunshine.
(b) Explain why your answers are only estimates.