If probability of X to fail in examination is 0.3 and that for Y is 0.2 , then probability that eith

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14.Probability

medium

If the probability of $X$ to fail in the examination is $0.3$ and that for $Y$ is $0.2$, then the probability that either $X$ or $Y$ fail in the examination is

A

$0.5$

B

$0.44$

C

$0.6$

D

None of these

(IIT-1989)

Solution

(b) Here $P(X) = 0.3;$ $P(Y) = 0.2$

Now $P(X \cup Y) = P(X) + P(Y) – P(X \cap Y)$

Since these are independent events, so

$P(X \cap Y) = P(X)\,.\,P(Y)$

Thus required probability $ = 0.3 + 0.2 – 0.06 = 0.44$.

Standard 11

Mathematics

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