Apps. and Interpretation for IBDP Maths Ebook 1 | Page 237

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Paper 1 – Cumulative Frequency Table
Example
The following table gives the examination scores for 60 students.
(a)
Score Number of students Cumulative frequency
20 15 15
40 30 45
60 5 p
80 q 60
Find the value of
17
(i) p ;
(b)
(c)
(d)
(ii) q .
Find the mean score.
Write down the standard deviation.
State whether the data is discrete or continuous.
[3]
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[1]
Solution
(a) (i) p �45 � 5
p � 50
A1 N1
(b)
(ii) q �60 � 50
(M1) for valid approach
q � 10
A1 N2
The mean score
(20)(15) � (40)(30) � (60)(5) � (80)(10)
�
60
(A1) for correct formula
� 43.33333333
� 43.3
A1 N2
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