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JEE Advanced · Mathematics · 32. Probability

Let X denote the number of elements in set X. Let S=1, 2, 3, 4, 5, 6 be a sample space, where each element is equally likely to occur. If A and B are independent events associated with S, then the number of ordered pairs A, B such that 1B<A, equals

  1. A 459
  2. B 421
  3. C 138
  4. D 422
Verified Solution

Answer & Solution

Correct Answer

(D) 422

Step-by-step Solution

Detailed explanation

Since A and B are independent events
PAB=PAPB
ABS=AS·BS
S AB=A·Bx=number of element in set
S=6
6AB=AB
6nAB=nAnBset x=nx
Case I:
nAB=1
nAnB=6
a nA=6, nB=1Number of ways=C6 6×C1 6=6 b nA=3, nB=1  Number of ways=C36×C13×C25=180
From JEE Advanced
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