JEE Main & Advanced Mathematics Probability Question Bank Definition of probability

  • question_answer
    The probability that in a year of the 22nd century chosen at random there will be 53 Sundays is               [Orissa JEE 2003]

    A)                 \[\frac{3}{28}\]    

    B)                 \[\frac{2}{28}\]

    C)                 \[\frac{7}{28}\]    

    D)                 \[\frac{5}{28}\]

    Correct Answer: D

    Solution :

               We know a leap year is fallen within 4 years, so its probability is \[\frac{25}{100}=\frac{1}{4}\]            53rd Sunday is a leap year \[=\frac{1}{4}\times \frac{2}{7}\,=\,\frac{2}{28}\]            Similarly probability of 53rd Sunday in a non-leap year \[=\frac{75}{100}\times \frac{1}{7}\,=\frac{3}{4}\times \frac{1}{7}=\frac{3}{28}\]                 \ Required probability \[=\frac{2}{28}+\frac{3}{28}=\frac{5}{28}.\]


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