60 students were each asked how many hours of screen time they had in a day.
The results are shown in the table.
| Screen time (\(t\), hours) | \(0\leq t<2\) | \(2\leq t<4\) | \(4\leq t<6\) | \(6\leq t<8\) | \(8\leq t<10\) | \(10\leq t<12\) |
|---|
| Frequency | \(4\) | \(7\) | \(15\) | \(19\) | \(11\) | \(4\) |
Find the interval that contains the median screen time.[1]
Calculate an estimate of the mean daily screen time.[1]
Calculate an estimate of the standard deviation of the screen time.[1]
Three students are selected at random from the survey.
Find the probability that two of them have less than 6 hours of screen time and the other has at least 8 hours of screen time.[3]
60 adults were also asked how many hours of screen time they had in day.
The results are summarised in the table.
| Mean | \(5.23\) |
| Standard deviation | \(1.89\) |
Make two comparisons between the number of hours of screen time by the adults and by the students.[2]
Another 10 adults were asked how many hours of screen time they had in a day. The data was added to the study.
The estimated mean hours of screen time by the adults is now 5.4 hours.
Explain what this tells you about the number of hours of screen time of the adults added to the study.[1]