Probability Ques 43
Question-
$X$ and $Y$ appear in an interview. The probability of X’s selection is $\frac{1}{5}$ th and the probability of Y’s selection is $\frac{2}{7}$ th. What is the probability that only one of them is selected?
(1) $\frac{12}{19}$
(2) $\frac{11}{15}$
(3) $\frac{13}{35}$
(4) $\frac{15}{44}$
(5) $\frac{10}{27}$
(IBPS RRBs Officer Scale-I CWE Main Exam, 13.10.2019)
Show Answer
Correct Answer: (3)
Solution: (3)
The required probability $=X$ is selected and $Y$ is rejected and $Y$ is selected and $X$ is rejected $=\frac{1}{5} \times\left(1-\frac{2}{7}\right)+\left(1-\frac{1}{5}\right) \times \frac{2}{7}$ $=\left[\left(\frac{1}{5}\right) \times\left(\frac{5}{7}\right)\right]+\left[\left(\frac{4}{5}\right) \times\left(\frac{2}{7}\right)\right]$ $=\frac{5}{35}+\frac{8}{35}=\frac{13}{35}$
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