Statistics

The table shows the number of goals scored in 25 matches.

Number of goals	0	1	2	3	4
Frequency	5	9	7	3	1

Work out the mean number of goals per match.

60 fish are caught, tagged and released. Later 50 fish are caught and 12 of them are tagged. Estimate the number of fish in the lake and state one assumption.

From a cumulative frequency graph for 80 students' test marks, the lower quartile is 34, the median 47 and the upper quartile 58. (a) Find the interquartile range. (b) Compare with another class whose median is 50 and IQR is 12.

Two groups sat a test. Group A: minimum 21, lower quartile 35, median 48, upper quartile 60, maximum 78. Group B: minimum 30, lower quartile 44, median 52, upper quartile 57, maximum 70. Compare the distributions of the two groups.

The table shows times taken by commuters.

Time, t (minutes)	Frequency
0 < t ≤ 10	18
10 < t ≤ 15	24
15 < t ≤ 20	30
20 < t ≤ 30	26
30 < t ≤ 50	12

Calculate the frequency density for each class, ready to draw a histogram.