JEE MainMathematicsProbabilityMCQ+4 / −1
A fair die is thrown until 2 appears. Then the probability, that 2 appears in even number of throws, is
- A
- B
- C
- D
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Correct answer: A
-
Let the random variable denote the throw on which the first appears.
-
Since the die is fair:
- Probability of getting a on any throw is
- Probability of not getting a is
-
We need the probability that the first appears on an even-numbered throw:
-
Using geometric distribution, So for even ,
-
Factor this as a geometric series: Since we get
-
Substitute and :
-
Simplify:
-
Therefore, the required probability is
-
Comparing with the options:
- A: ✅
- B:
- C:
- D:
Hence, the correct option is A.
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