Question
The sum of probabilities of two mutually exclusive events will always be 1.
Answer: Option B
:
B
The sum of probabilities of two mutually exclusive events need not be always1.
For example, consider the events “getting a prime number”, and “getting a composite number” for the experiment ofrolling a die. They are mutually exclusive, but the sum of their probabilities is less than 1.
Favorable outcomes for prime no. = 2 , 3, 5
Favorable outcomes for composite no. = 4, 6
P(getting a prime no.) =36=12
P(getting a composite no.) =26=13
12+13≠1. SoThe sum of probabilities of two mutually exclusive events need not be always1.
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B
The sum of probabilities of two mutually exclusive events need not be always1.
For example, consider the events “getting a prime number”, and “getting a composite number” for the experiment ofrolling a die. They are mutually exclusive, but the sum of their probabilities is less than 1.
Favorable outcomes for prime no. = 2 , 3, 5
Favorable outcomes for composite no. = 4, 6
P(getting a prime no.) =36=12
P(getting a composite no.) =26=13
12+13≠1. SoThe sum of probabilities of two mutually exclusive events need not be always1.
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