Statistics

The table shows the number of goals scored in 30 matches.

Number of goals	1	2	3	4	5
Frequency	4	10	8	6	2

Work out the mean number of goals per match.

80 fish are caught, tagged and released. Later 75 fish are caught and 15 of them are tagged. Estimate the number of fish in the lake and state one assumption.

Two groups sat a test. Group A: minimum 12, lower quartile 20, median 31, upper quartile 38, maximum 50. Group B: minimum 8, lower quartile 24, median 27, upper quartile 36, maximum 44. Compare the distributions of the two groups.

A school has 180 students in Year 10, 220 students in Year 11. A stratified sample of 40 students is taken. How many should be from Year 10?

The table shows times taken by commuters.

Time, t (minutes)	Frequency
0 < t ≤ 20	16
20 < t ≤ 30	22
30 < t ≤ 40	28
40 < t ≤ 60	24
60 < t ≤ 100	20

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