Apps. and Interpretation for IBDP Maths Ebook 1 | страница 276

Your Practice Set – Applications and Interpretation for IBDP Mathematics
2. The following table shows the probability distribution of a discrete random variable X .
x 0 20 40 60
P( X � x)
1
10
1
5
2
5
k
(a) Find the value of k .
(b) Find E( X ) .
[2]
[3]
3. The following table shows the probability distribution of a discrete random variable X .
It is given that k � 0 .
x 1 2 k
P( X � x)
1
14
4
14
2
k
14
(a) Find the value of k .
(b) Find E( X ) .
The observation of X is recorded for two times. Let Y be the sum of these two
observations.
[3]
[3]
(c) Find P( Y � 3) .
[2]
4. The following table shows the probability distribution of a discrete random variable X .
x k k � 1 k � 2 8
P( X � x)
k 1 k 1
2 8 4 8
(a) Find the value of k .
(b) Find E( X ) .
The observation of X is recorded for two times. Let Y be the product of these two
observations.
[3]
[3]
(c) Find P( Y � 2) .
[2]
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