Apps. and Interpretation for IBDP Maths Ebook 1 | Page 355

(f)
Solution
Two students are selected at random. Find the probability that both of them
choose Mexico.
[3]
(a) (i) H
0
: The gender of a student and the choices
of overseas trips are independent. A1 N1
(ii) H
1
: The gender of a student and the choices
of overseas trips are not independent. A1 N1
(b) 3 A1 N1
(c)
� � 9.568627451
(A1) for correct value
2
calc
� � 9.57
A1 N2
2
calc
(d) The null hypothesis is rejected. A1
2
As � � 7.815 . A1 N2
calc
(e) (i) The required probability
4
� (A1) for correct formula
80
1
� A1 N2
20
[2]
[1]
[2]
[2]
(ii)
The required probability
10 � 7
� (A1) for correct formula
80
17
� A1 N2
80
23
(f)
(iii)
The required probability
12
�
(A1) for correct formula
22 �12
6
� A1 N2
17
The required probability
� 4 � 8 �� 4 � 8 �1�
� � �� �
(A2) for correct formula
� 80 �� 80 �1
�
33
� A1 N3
1580
[6]
[3]
www.seprodstore.com
345