(a(i))[3]
Use the grid to draw a cumulative frequency diagram for the data.
(a(ii)(a))[1]
Use your diagram to estimate the median.
(a(ii)(b))[2]
Use your diagram to estimate the interquartile range.
(b(i))[2]
Calculate the average number of errors.
(b(ii))[1]
One adult is selected at random. Find the probability that this adult made more than $3$ errors.
(b(iii))[2]
Two adults are selected at random. Find the probability that they each made exactly one error.