Analysis and Approaches for IBDP Maths Ebook 2 | Page 253

Exercise 79
1. The random variable X has the probability density function
1 3
f ( x)
� � x � , 1�x
� 3.
2 2
Find
(a) E( X ) ;
(b)
the interquartile range.
[2]
[5]
2. The random variable X has the probability density function
1
f( x)
� , �1� x � 2.
3
Find
(a) E( X ) ;
(b)
(b)
2
E( X ) ;
the standard deviation.
3. The random variable X has the probability density function
[2]
[2]
[2]
19
1
f ( x)
� e
2
e �1
x
, 0�x
� 2.
(a)
(b)
Write down the mode.
Find the exact value of the median.
[1]
[4]
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