Analysis and Approaches for IBDP Maths Ebook 1 | Page 221

Front Page
73
Paper 1 Section A – Effects of coding in data
Example
There are 20 items in a data set. The sum of the items is 100.
(a)
Find the mean.
The variance of this data set is 2. Each value in the set is multiplied by 7.
[2]
(b) (i) Write down the value of the new mean.
(ii)
Find the value of the new variance.
[3]
17
Solution
(a) The mean
100
�
20
(A1) for correct formula
� 5
A1 N2
(b) (i) 35 A1 N1
[2]
(ii)
The new variance
2
� (7 )(2)
(M1) for valid approach
� 98
A1 N2
[3]
Exercise 73
1. There are 15 items in a data set. The sum of the items is 150.
(a)
Find the mean.
The variance of this data set is 8. Each value in the set is multiplied by 3.
[2]
(b) (i) Write down the value of the new mean.
(ii)
Find the value of the new variance.
[3]
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