Analysis and Approaches for IBDP Maths Ebook 1 | Page 262

Your Practice Set – Analysis and Approaches for IBDP Mathematics
Exercise 85
1. A five-sided fair die has three blue faces and two red faces. The die is rolled for two
times.
Let F be the event a blue face lands down in the first roll, and S be the event a blue face
lands down in the second roll.
The information above is shown on the following tree diagram.
(a)
Find
(b)
(i) P( F� S)
;
(ii) P( S ) .
Find the probability that
[4]
(i)
a red face lands down for two times;
(ii) a blue face lands down in the first roll, given that a red face lands down in
the second roll.
[5]
Rossi plays a game where he rolls the die for two times. If a blue face lands down, he
scores 4. If the red face lands down, he scores 1. Let X be the total score obtained.
(c)
Copy and complete the probability distribution table.
X 2 5 8
P( X � x)
[3]
(d) Calculate the expected value of X .
[2]
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