The times, t t\,t hours, spent on a task are grouped below.
| Time | 0<t≤40<t\leq40<t≤4 | 4<t≤84<t\leq84<t≤8 | 8<t≤128<t\leq128<t≤12 |
|---|---|---|---|
| Frequency | 4 | aaa | 2 |
Using class midpoints, the estimated mean is given as 5 hours.
Show that a=2a=2a=2.
Calculate an estimate of the variance.
278 exam-style questions on CCEA A Level Maths 2.5 Data presentation and interpretation, covering 2.5.1 Data presentation and interpretation, 2.5.2 Data presentation and interpretation, 2.5.3 Data presentation and interpretation, 2.5.4 Data presentation and interpretation, 2.5.5 Data presentation and interpretation, 2.5.6 Data presentation and interpretation, 2.5.7 Data presentation and interpretation, 2.5.8 Data presentation and interpretation, 2.5.9 Data presentation and interpretation, and 2.5 Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.