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11th Class Mental Ability Probability Question Bank Question - Probability

  • question_answer
    In a class, 30% of the students offered English. 20% offered Hindi and 10% offered both. If a student is selected at random, what is the probability that he has offered English or Hindi?

    A) \[\frac{2}{5}\]

    B) \[\frac{3}{4}\]

    C) \[\frac{3}{5}\]

    D) \[\frac{3}{10}\]

    E) None of these

    Correct Answer: A

    Solution :

    Explanation Option (a) is correct. \[P\,(E)=\frac{30}{100}=\frac{3}{10},\,P(H)=\frac{20}{100}=\frac{1}{5}\,\,and\,\,P(E\cap H)=\frac{10}{100}=\frac{1}{10}\] \[P\,(E\,\,or\,\,H)=P(E\cup H)+P(E)+P(H)-P(E\cap H)\] \[=\left( \frac{3}{10}+\frac{1}{5}+\frac{1}{10} \right)=\frac{4}{10}=\frac{2}{5}.\]


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