(a)[4]
Calculate an estimate for the mean time needed to complete the race.
(b)[3]
Two of the 80 people are chosen at random. Find the probability that one takes 30 minutes or less and the other takes more than 60 minutes to complete the race.
Mathematics 4024 · O Level · Averages and measures of spread
Averages and measures of spread — practice question
The table gives the times needed by 80 people to finish a race.