NIMCET 2013 — Mathematics PYQ
NIMCET | Mathematics | 2013If A and B are two events such that P(A∪B)=65, P(A∩B)=31 and P(Bˉ)=21, then the events A and B are:
Choose the correct answer:
- A.
Dependent
- B.
Independent
(Correct Answer) - C.
Mutually exclusive
- D.
None of these
Independent
Explanation
Solution
1. Find P(B):
Given P(Bˉ)=21.
P(B)=1−P(Bˉ)=1−21=21
2. Find P(A) using the Addition Theorem of Probability:
P(A∪B)=P(A)+P(B)−P(A∩B)
65=P(A)+21−31
65=P(A)+63−2
65=P(A)+61
P(A)=65−61=64=32
3. Check for Independence:
Events are independent if P(A∩B)=P(A)×P(B).
P(A)×P(B)=32×21=31
Given P(A∩B)=31.
Since P(A∩B)=P(A)×P(B), the events A and B are Independent.
Explanation
Solution
1. Find P(B):
Given P(Bˉ)=21.
P(B)=1−P(Bˉ)=1−21=21
2. Find P(A) using the Addition Theorem of Probability:
P(A∪B)=P(A)+P(B)−P(A∩B)
65=P(A)+21−31
65=P(A)+63−2
65=P(A)+61
P(A)=65−61=64=32
3. Check for Independence:
Events are independent if P(A∩B)=P(A)×P(B).
P(A)×P(B)=32×21=31
Given P(A∩B)=31.
Since P(A∩B)=P(A)×P(B), the events A and B are Independent.
