The blood groups of 50 students in a school are recorded as follows:
A, B, O, O, AB, A, O, B, B, O,
O, AB, A, O, B, A, O, B, O, A,
B, O, O, A, AB, B, O, A, O, B,
O, A, B, O, AB, O, A, B, O, A,
O, B, A, O, AB, O, B, O, A, O
(i) Construct a frequency table for the four blood groups.
(ii) Using an appropriate measure of central tendency, identify the blood group that is most common among the students.
(iii) Explain in about three sentences why the other two measures of central tendency are not suitable for summarising this categorical data.