Three students S1, S2, and S3 are given a problem to solve. Consider the following events:
U: At least one of S1, S2, and S3 can solve the problem,
V: S1₁ can solve the problem, given that neither S2 nor S3 can solve the problem,
W: S2 can solve the problem and S3 cannot solve the problem,
T: S3 can solve the problem.
For any event E, let P(E) denote the probability of E. If
Then P(T) is equal to
Correct Answer :
13/36
Solution :
Let , , and be the independent events that students 1, 2, and 3 solve the problem, respectively. Let their probabilities be denoted as:
, , and .
The events given in the problem can be expressed as follows:
1. Event U: At least one of the students can solve the problem.
The probability of event is the complement of none of the students being able to solve the problem:
Given that , we have:
(Equation 1)
2. Event V: can solve the problem, given that neither nor can solve the problem.
Since the events are independent, the conditional probability simplifies to:
Given that , we get:
Substituting into Equation 1:
(Equation 2)
3. Event W: can solve the problem and cannot solve the problem.
Given that , we have:
(Equation 3)
4. Finding P(T):
We need to find the probability of event , which is .
Let us expand Equation 2:
Substitute the value of from Equation 3 into the expanded expression:
Finding a common denominator (36):
Therefore, the probability is equal to .
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