J & K CET Engineering J and K - CET Engineering Solved Paper-2014

  • question_answer
    Events A, B and C are mutually exclusive events such that \[P(A)=(3x+1)/3,\]  \[P(B)=(x-1)/4,\] \[P(C)=(1-2x)/2,\] Find the set of possible value of x in the interval.

    A)  \[[-1/3,\,\,1/2]\]       

    B)  \[[1/3,\,2/3]\]

    C)  \[[1/3,\,13/3]\]       

    D)  \[[0,1]\]

    E)  None of these

    Correct Answer: E

    Solution :

    Given, \[P(A)=\frac{3x+1}{3},\] \[P(B)=\frac{1-x}{4}\] and \[P(C)=\frac{1-2x}{2}\] Since, A,B and C are mutually exclusive events. \[\therefore \] \[0\le \frac{3x+1}{3}\le 1,\,0\le \frac{1-x}{4}\le 1,\,0\le \frac{1-2x}{2}\le 1\] and \[0\le \frac{3x+1}{3}+\frac{1-x}{4}+\frac{1-2x}{2}\le 1\] \[\Rightarrow \]  \[0\le 3x+1\le 3,0\le 1-x\le 4,0\le 1-2x\le 2\] \[\Rightarrow \] \[-1\le 3x\le 2,-1\le -x\le 3,-1\le -2x\le 1\] \[\Rightarrow \] \[\frac{-1}{3}\le x\le \frac{2}{3},-3\le x\le 1,-\frac{1}{2}\le x\le \frac{1}{2}\] ?.(i) and \[0\le \frac{4(3x+1)+3(1-x)+6(1-2x)}{12}\le 1\] \[\Rightarrow \] \[0\le -3x+13\le 12\] \[\Rightarrow \] \[-13\le -3x\le -1\] \[\frac{1}{3}\le x\le \frac{13}{3}\] ?.(ii) \[\therefore \]   From Eq (i) and (ii), we get \[\frac{1}{3}\le \frac{1}{2}\] \[\therefore \] \[x\in \left[ \frac{1}{3},\frac{1}{2} \right]\]


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