JEE Main & Advanced Mathematics Probability Question Bank Self Evaluation Test - Probability-II

  • question_answer
    A die is rolled three times. Let \[{{E}_{1}}\] denote the event of getting a number larger than the previous number each time and \[{{E}_{2}}\] denote the event that the numbers (in order) form an increasing AP then

    A) \[P({{E}_{2}})\ge P({{E}_{1}})\]

    B) \[P({{E}_{2}}\cap {{E}_{1}})=\frac{3}{10}\]

    C) \[P({{E}_{2}}/{{E}_{1}})=\frac{1}{36}\]

    D) \[P({{E}_{1}})=\frac{10}{3}P({{E}_{2}})\]

    Correct Answer: D

    Solution :

    [d] \[P({{E}_{1}})=\frac{^{6}{{C}_{3}}}{216}=\frac{5}{54};P({{E}_{2}})=\frac{4+2}{216}=\frac{1}{36}\] \[{{E}_{1}}\cap {{E}_{2}}={{E}_{2}}\therefore P({{E}_{1}}\cap {{E}_{2}})=P({{E}_{2}})=1/36\] \[P({{E}_{2}}/{{E}_{1}})=\frac{P({{E}_{1}}\cap {{E}_{2}})}{P({{E}_{1}})}=\frac{1/36}{5/54}=\frac{54}{180}=\frac{3}{10}.\]


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