Analysis and Approaches for IBDP Maths Ebook 2 | Page 297

Answers
78.4 (a) k � 4
(b)
103
Var( X ) �
64
Chapter 19
Exercise 79
79.1 (a)
79.2 (a)
5
E( X ) �
3
(b) �1�
3
(b)
(c)
3
4
79.3 (a) 2
(b)
79.4 (a) 3
(b) 1
(c)
Exercise 80
1
E( X ) �
2
2
E( X ) � 1
2
�e
�1�
ln � �
� 2 �
3 3 �1
E( X ) �
6
80.1 (a) k � 6
(b)
45
E( X ) �
32
(c) 1.41
(d)
� 5 � 13
P�X
� ��
� 4 � 16
(e)
�
P�X
�
7 5 � 1
� X � ��
4 4 � 26
80.2 (a) E( X ) �� 1.83
(b) 3.87
(c)
3
P( X �0)
�
4
(d)
1
P( X � ��
| X � 0) �
2
(e) r �� 0.644
80.3 (a) Refer to solution
(b) E( X ) � 2.55
(c)
(d)
1
4 � �
Refer to solution
(e)
2
1�
2
80.4 (a)
73
E( X ) �
60
(b) 2
(c) 1.51
(d) 0.742
(e)
137
P( X �2)
�
360
(f) P( X � 2 | X
128
� 2) �
137
Chapter 20
Quick Practice
I (a) (1)
e �1
2
e
(2)
e �1
2
2e
(3)
e �1
0 � A1 �
2
2e
(b) (1)
e �1
3
2e
(2)
e �1
0 � A2 �
3
2e
(c)
e �1
0 � A3 �
4
2e
(d)
e �1
0 � An
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