Subject

    Quantitative Aptitude

    Topic

    Probability

    A brother and a sister appear for an interview against two vacant posts in an office. The probability of the brother’s selection is 1/5 and that of the sister’s selection is 1/3. What is the probability that only one of them is selected?

    ক)
    1/5
    খ)
    3/4
    গ)
    2/5
    ঘ)
    3/5

    Explanation

    Probability that only one of them is selected = (prob. that brother is selected) × (prob. that sister is not selected) +  (Prob. that brother is not selected) × (Prob. that sister is selected) = (15×23)+(45×13)\left(\frac15\times\frac23\right)+\left(\frac45\times\frac13\right) = 25\frac25

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