JEE Main & Advanced JEE Main Paper (Held On 26 May 2012)

  • question_answer
    There are two balls in an urn. Each ball can be either white or black. If a white ball is put into the um and there after a ball is drawn at random from the um, then the probability that it is white is.   JEE Main Online Paper (Held On 26-May-2012)  

    A) \[\frac{1}{4}\]                                   

    B) \[\frac{2}{3}\]

    C) \[\frac{1}{5}\]                                   

    D) \[\frac{1}{3}\]

    Correct Answer: B

    Solution :

    Total possible event when one ball is taken out \[{{=}^{3}}{{C}_{1}}\] Let E : The event of 1 white ball coming out No. of ways to 1 white ball coming out\[{{=}^{2}}{{C}_{1}}\] \[\therefore \]\[P(E)=\frac{^{2}{{C}_{1}}}{^{3}{{C}_{1}}}=\frac{2}{3}\]


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