A-LevelMathematicsProbability and statistics9709/52 · Oct/Nov 2020 · Q59 Marks
The following table gives the weekly snowfall, in centimetres, for 11 weeks in 2018 at two ski resorts, Dados and Linva. Dados 6 8 12 15 10 36 42 28 10 22 16 Linva 2 11 15 16 0 32 36 40 10 12 9
- (a)Represent the information in a back-to-back stem-and-leaf diagram.[4]
- (b)Find the median and the interquartile range for the weekly snowfall in Dados.[3]
- (c)The median, lower quartile and upper quartile of the weekly snowfall for Linva are 12, 9 and 32 cm respectively. Use this information and your answers to part (b) to compare the central tendency and the spread of the weekly snowfall in Dados and Linva.[2]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2020). The mark or mark type is shown in brackets.
- [B1] Correct stem can be upside down, ignore extra values
- [B1] Correct Dados labelled, leaves in order and lined up vertically (less than midway to next column), no commas etc, no extra terms
- [B1] Correct Linva on opposite side of stem labelled, leaves in order and lined up vertically (less than midway to next column), no commas etc, no extra terms
- [B1] Correct single key for their diagram, need both resorts identified and 'cm' stated at least once here or in leaf headings or title. SC If 2 separate diagrams drawn, SCB1 if both keys meet these criteria B0B1B0SCB1 max.
- [B1] Correct
- [M1] 22 < UQ < 36 – 8 < LQ < 10
- [A1] WWW
- [B1 FT] FT from their 5(b) values for Dados. Statement comparing central tendency in context
- [B1 FT] Statement comparing spread in context Note: simply stating and comparing the values is not sufficient.
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