Question:medium

Probability of occurrence of an event A is 1/2 and that of B is 3/10. If A and B are mutually exclusive, then the probability of occurrence of neither A nor B is

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For mutually exclusive events, think of probability as just adding areas. If A covers 50% of the space and B covers 30% (with no overlap), together they cover 80%. What's left over ("neither") is simply $100% - 80% = 20%$, which is $1/5$.
Updated On: Apr 29, 2026
  • $\frac{4}{5}$
  • $\frac{3}{5}$
  • $\frac{2}{5}$
  • $\frac{1}{5}$
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The Correct Option is D

Solution and Explanation

To find the probability of occurrence of neither event A nor event B, we first need to understand that A and B are mutually exclusive events. This means that both events cannot occur at the same time. Therefore, the probability of occurrence of either A or B is given by the sum of their individual probabilities.

The probability of occurrence of event A, \(P(A) = \frac{1}{2}\), and the probability of occurrence of event B, \(P(B) = \frac{3}{10}\).

Since A and B are mutually exclusive, the probability of occurrence of either A or B is:

\(P(A \cup B) = P(A) + P(B)\)

Substituting the values, we get:

\(P(A \cup B) = \frac{1}{2} + \frac{3}{10}\)

To add these fractions, we need a common denominator:

\(\frac{1}{2} = \frac{5}{10}\)

Hence,

\(P(A \cup B) = \frac{5}{10} + \frac{3}{10} = \frac{8}{10} = \frac{4}{5}\)

The probability of occurrence of neither A nor B is the complement of the probability of occurrence of either A or B:

\(P(\text{neither } A \text{ nor } B) = 1 - P(A \cup B)\)

Substituting the calculated result:

\(P(\text{neither } A \text{ nor } B) = 1 - \frac{4}{5} = \frac{1}{5}\)

Therefore, the probability of occurrence of neither A nor B is \(\frac{1}{5}\). Hence, the correct answer is:

\(\frac{1}{5}\)

The correct option is: Option 4: \(\frac{1}{5}\)

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