Multiple choice

What is the chance that a leap year, selected at random, will contain fifty three Sundays ?

  1. $\dfrac{6}{7}$
  2. $\dfrac{2}{7}$
  3. $\dfrac{4}{7}$
  4. $\dfrac{3}{7}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A leap year has 366 days, which is 52 weeks and 2 extra days. The possible pairs for the 2 extra days are (Sun, Mon), (Mon, Tue), (Tue, Wed), (Wed, Thu), (Thu, Fri), (Fri, Sat), (Sat, Sun). Two of these seven outcomes include a Sunday.

AI explanation

A leap year has 366 days, which equals 52 weeks and 2 extra days. For the year to have 53 Sundays, one of these 2 extra days must be a Sunday. The 2 extra days can be pairs like Friday and Saturday or Saturday and Sunday, giving 7 equally likely combinations, of which 2 include a Sunday. Therefore, the required probability is 2/7.

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