A net was used to catch swallows so that they could be ringed and examined. The weights of 55 adult birds were recorded and the results are summarised in the table below.
Weight (g)
\(14 - 19\)
\(20 - 21\)
\(22 - 23\)
\(24 - 25\)
\(26 - 29\)
\(30 - 35\)
Frequency
3
6
15
20
9
2
For these data calculate estimates of
the median,
the \(33 ^ { \text {rd } }\) percentile.
These data are represented by a histogram and the bar representing the 24-25 group is 1 cm wide and 20 cm high.
Calculate the dimensions of the bars representing the groups