9 . The random variable X has the probability density function
� 1 1 � x� �4� x� 0
20 5 � 1 2 2 1
f ( x) � �� x � x � 0 � x � 3 . � 15 15 5 � 0 otherwise � �
( a ) Find the standard deviation of X if
( b ) Find P ( X � 2 ) .
13 E ( X ) � .
60 [ 3 ]
[ 3 ]
© SE Production Limited 15 All Rights Reserved 2021