NCERT Class XII Mathematics Chapter - - Solutions

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Question : 32
Total: 101
One card is drawn at random from a well shuffled deck of 52 cards. In which of the following cases are the events E and F independent?
(i) E : ‘the card drawn is a spade’ ; F : ‘the card drawn is an ace’
(ii) E : ‘the card drawn is black’ ; F : ‘the card drawn is a king’
(iii) E : ‘the card drawn is a king or queen’ ; F : ‘the card drawn is a queen or jack’.
Solution:  
(i) P(E)=
13
52
=
1
4
and P(F)=
4
52
=
1
13

P(EF)=
1
52
=
1
4
×
1
13
=P(E)P(F)
⇒ E and F are independent.
(i) P(E)=
26
52
=
1
2
and P(F)=
4
52
=
1
13

P(EF)=
2
52
=
1
26
=
1
2
×
1
13
=P(E)P(F)
⇒ E and F are independent.
(iii) P(E)=
4
52
+
4
52
=
2
13
and P(F)=
4
52
+
4
52
=
2
13

P(EF)=
4
52
=
1
13
2
13
×
2
13

P(EF)P(E)P(F)
⇒ E and F are not independent.
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