Averages (including IQR): Eduqas GCSE Foundation November 2018 Paper 2 Q24

Foundation November 2018 Paper 2 Q24

EduqasFoundationCurrent spec2 marksAverages (including IQR)Rounding

24. Gary measures the depth of a river in 6 places between two bridges.
The depths are as follows:

48·8 cm 55·1 cm 34·6 cm 75·2 cm 85·7 cm 96·1 cm

Gary decides to write each of the 6 depths correct to the nearest 10 cm.
He states that the median depth of the river between the two bridges is 70 cm.

Give two reasons why the method Gary used to obtain this median depth leads to an inaccurate result. [2]

Reason 1:

Reason 2:

Mark scheme

Scheme	Marks	Comments
Two unique possible reasons: • Didn’t use raw data	E1	E1 for any 1 possible reason Didn’t use raw data includes, e.g. ‘median is (actually) 65(.15 cm)’ ‘used rounded results’ ‘depths were to the nearest 10 cm’
• Insufficient data	E1	Insufficient data includes, e.g. ‘needs to take more readings of depth’ ‘only recorded at one time of the day’ ‘may only have taken readings near the banks of the river’ If the actual median is calculated it must be correct or approximately 65 (cm) Depths recorded in order are 30, 50, 60, 80, 90, 100
	(2)