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Question: Answered & Verified by Expert
The probabilities of three events A,B and C are given PA=0.6, PB=0.4 and PC=0.5. If PAB=0.8, PAC=0.3, PABC=0.2, PBC=β and PABC=α, where 0.85α0.95, then β lies in the interval :
MathematicsProbabilityJEE MainJEE Main 2020 (06 Sep Shift 2)
Options:
  • A 0.35, 0.36
  • B 0.25, 0.35
  • C 0.20, 0.25
  • D 0.36, 0.40
Solution:
1794 Upvotes Verified Answer
The correct answer is: 0.25, 0.35

PABC=P(A)+P(B)+P(C)-P(AB)-P(BC)-P(CA)+PABC

α=1.4-p(AB)-β

α+β=1.4-p(AB)....(1)

again

P(AB)=P(A)+P(B)-P(AB)

P(AB)=·2......(2)

by 1 and 2

α=1.2-β

now

0.85α0.95

0.851.2-β0.95β0.25,0.35

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