(a)[2]
Use the diagram to work out an estimate of the interquartile range.
(b)[2]
$20\%$ of the adults are awarded a prize for achieving a high quiz score. Use the diagram to calculate the minimum score required to win a prize.
(c)[2]
From the diagram, complete the frequency table for the score intervals $0 < s \le 20$, $20 < s \le 40$, $40 < s \le 60$, $60 < s \le 80$, $80 < s \le 100$.