A group of students each complete a puzzle. The table shows the time, t seconds, each student took to complete the puzzle. Time (t seconds) | 80<t≤120 | 120<t≤140 | 140<t≤150 | 150<t≤240 Frequency | 13 | 26 | 27 | 24 Find the number of students who took 2 minutes 20 seconds or less to complete the puzzle.

1. (a)(i)A group of students each complete a puzzle. The table shows the time, t seconds, each student took to complete the puzzle. Time (t seconds) | 80<t≤120 | 120<t≤140 | 140<t≤150 | 150<t≤240 Frequency | 13 | 26 | 27 | 24 Find the number of students who took 2 minutes 20 seconds or less to complete the puzzle.[1]
2. (a)(ii)Calculate an estimate of the mean time taken, in seconds, to complete the puzzle.[3]
3. (b)(i)A group of adults also completed this puzzle. A cumulative frequency diagram for their times is shown. [Figure with cumulative frequency diagram] Use the cumulative frequency diagram to complete the frequency table. Time (t seconds) | 50<t≤100 | 100<t≤150 | 150<t≤200 | 200<t≤250 | 250<t≤300 Frequency | 8 | | | |[2]
4. (b)(ii)Use the cumulative frequency diagram to find an estimate of the median.[1]
5. (b)(iii)55% of the adults took between 125 seconds and k seconds to complete the puzzle. Use the cumulative frequency diagram to find the value of k.[3]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.