Analysis and Approaches for IBDP Maths Ebook 1 | Seite 283

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3. The random variable X is normally distributed with a mean of 1.5. The following
diagram shows the normal curve for X .
Let R be the shaded region under the curve, to the right of 2.7. The area of R is 0.07.
(a) Write down P( X � 2.7) .
(b) Find P(1.5 � X � 2.7) .
(c) Find P( X � 0.3) .
[1]
[3]
[2]
4. The random variable X is normally distributed with a mean of 6 . The following
11
diagram shows the normal curve for X .
Let R be the shaded region under the curve, to the left of 3
11 . The area of R is 1 6 .
21
(a)
Write down
� 3 �
P�X
� �
� 11� . [2]
(b)
If
3
P( X � d) � P
�
�X
�
�
�
� 11� , find d . [2]
(c)
Find
� 3 �
P�
� X �d�
� 11 � . [2]
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