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Date May 2008 Marks available 1 Reference code 08M.1.sl.TZ1.9
Level SL only Paper 1 Time zone TZ1
Command term Write down Question number 9 Adapted from N/A

Question

The table below shows the number of words in the extended essays of an IB class.

Draw a histogram on the grid below for the data in this table.

[3]
a.

Write down the modal group.

[1]
b.

The maximum word count is \(4000\) words.

Write down the probability that a student chosen at random is on or over the word count.

[2]
c.

Markscheme

     (A3)     (C3)

Notes: (A3) for correct histogram, (A2) for one error, (A1) for two errors, (A0) for more than two errors.
Award maximum (A2) if lines do not appear to be drawn with a ruler.
Award maximum (A2) if a frequency polygon is drawn.

[3 marks]

a.

\({\text{Modal group}} = 3800 \leqslant w < 4000\)     (A1)     (C1)

[1 mark]

b.

\({\text{Probability}} = \frac{3}{{35}}{\text{ }}(0.0857{\text{, }}8.57\% )\)     (A1)(A1)     (C2)

Note: (A1) for correct numerator (A1) for correct denominator.

[2 marks]

c.

Examiners report

A surprising number of the candidates did not appear to have brought a ruler/straight edge and so lost a mark in this question as they were asked to draw a histogram which means the lines must be drawn using a ruler/straight edge. Some candidates drew a frequency polygon. Parts (b) and (c) were generally answered well though \(20/35\) was seen occasionally in part (c).

a.

A surprising number of the candidates did not appear to have brought a ruler/straight edge and so lost a mark in this question as they were asked to draw a histogram which means the lines must be drawn using a ruler/straight edge. Some candidates drew a frequency polygon. Parts (b) and (c) were generally answered well though \(20/35\) was seen occasionally in part (c).

b.

A surprising number of the candidates did not appear to have brought a ruler/straight edge and so lost a mark in this question as they were asked to draw a histogram which means the lines must be drawn using a ruler/straight edge. Some candidates drew a frequency polygon. Parts (b) and (c) were generally answered well though \(20/35\) was seen occasionally in part (c).

c.

Syllabus sections

Topic 2 - Descriptive statistics » 2.5 » For grouped discrete and continuous data: estimate of a mean; modal class.
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