12th Class Mathematics Sample Paper Mathematics Olympiad - Sample Paper-7

  • question_answer
    The probability that a leap year will have 53 Saturdays or 53 Sundays is

    A)  \[\frac{3}{7}\]                         

    B)  \[\frac{2}{7}\]            

    C)  \[\frac{1}{7}\]                         

    D)  None of these

    Correct Answer: A

    Solution :

    [a] Since, we know that a leap year contains 52 weeks and 2 odd days. 2 odd days may be (Sunday, Monday), (Monday, Tuesday), (Tuesday, Wednesday), (Wednesday, Thursday), (Thursday, Friday), (Friday, Saturday), (Saturday, Sunday). Let A = event of a leap year containing 53 Saturdays B = event of a leap year containing 53 Sundays. \[\therefore p(A)=\frac{2}{7},\,p(B)=\frac{2}{7}\] and\[P\left( A\cap B \right)=\frac{1}{7}\](According to above odd days possibility) \[\therefore \]Required probability, \[P\left( A\cap B \right)=P\left( A \right)+P\left( B \right)-P\left( A\cap B \right)\] \[=\frac{2}{7}\text{+}\frac{2}{7}\text{+}\frac{1}{7}=\frac{4-1}{7}=\frac{3}{7}\] Hence, option [a] is correct.


You need to login to perform this action.
You will be redirected in 3 sec spinner