A-LevelMathematicsProbability and statistics9709/62 · Feb/Mar 2017 · Q47 Marks

The weights in kilograms of packets of cereal were noted correct to 4 significant figures. The following stem-and-leaf diagram shows the data. 747 | 3 (1) 748 | 125779 (6) 749 | 022235556789 (12) 750 | 112223445677889 (15) 751 | 0023344455779 (13) 752 | 00011223444 (11) 753 | 2 (1) Key: 748 | 5 represents 0.7485 kg.

(i)On the grid, draw a box-and-whisker plot to represent the data.[5]
(ii)Name a distribution that might be a suitable model for the weights of this type of cereal packet. Justify your answer.[2]

This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.

Mark scheme

Marking points from the official mark scheme (Feb/Mar 2017). The mark or mark type is shown in brackets.

[M1] Attempt to find all 3 quartiles can be implied, Condone LQ=0.7496, Med=0.7506, UQ=0.7515
[B1] Correct median line in box using their scale
[A1] Correct quartiles in box
[B1] Correct end whiskers(not dots or boxes), lines not through box,
[B1] Correct uniform scale from at least 0.7473 to 0.7532, and label (wt) kg oe can be seen in title or scale
[B1] Normal
[B1] Symmetrical/peaks in middle or tails off quickly (Need symm + another reason)

On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.