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IB Maths AA SL 4.2 Data presentation

IB Maths AA SL 4.2 Data presentation
IB Mathematics: analysis and approaches guide, first assessment 2021

Practise reading and comparing data displays using medians, quartiles, IQR, class midpoints and positions in ordered data.

How this is tested

  • calculate medians and IQR from ordered values, box plots or grouped intervals using correct positions
  • explain why a median is unchanged when new values are placed either side of the middle of the data set
  • compare two distributions using medians and IQR, making the conclusion match the given context

Question 4(a)

[Maximum number: 1]

A teacher sets her class of 30 pupils a quiz.
Aiden and Brett were absent on the day of the quiz.
The following box and whisker diagram shows the results of the 28 pupils who took the quiz on the day.

Figure for Question 4(a) — IB Maths AA SL

Aiden and Brett take the quiz when they return.
Aiden scores less than 6.
Brett scores more than 17.

The mean score of the 28 pupils was 10.5.
The mean score for all 30 pupils is now 10.6.
The range of scores for all 30 pupils is 14.

Explain, briefly, why the median score for all 30 pupils would still be 10.5.