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probability q

  • 18-02-2015 11:32am
    #1
    itgirl268
    Registered Users Posts: 55 ✭✭


    A survey of students was carried out before an exam.
    20% of students stated that they were very condent, 50% stated that they
    were condent and 30% were uncondent.
    80% of those who said they were very condent, 50% of those who said they
    were condent and 20% of those who said they were uncondent got at least a
    B1 grade.
    Calculate
    (i) the probability that a randomly picked student got at least a B1 grade;
    (ii) given that the student got at least a B1 grade, the probability that he/she
    was very condent;
    (iii) given that the student got less than a B1 grade, the probability that he/she
    was uncondent.
    Tagged:


Comments

  • #2
    TheBody
    Registered Users Posts: 5,618 ✭✭✭TheBody


    I would begin by drawing out a tree diagram. It'll make your life much easier.

    Also, I presume you mean "confident" instead of "condent".


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