What Is the Probability of 53 Sundays and 52 Sundays in a Leap Year?
Learn how to calculate the probability of having 53 Sundays and 52 Sundays in a leap year with a clear explanation of the extra days involved.
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Probability of 53 Sundays in a leap year: 2/7. A leap year has 366 days, so it has 52 weeks and 2 extra days. These extra days can be any pair of consecutive days (e.g., Sunday-Monday, Monday-Tuesday). Since there are 7 possible pairs, each day occurs as one of these extra days 2 times out of 7. Probability of 52 Sundays: Simply 1 - (2/7) = 5/7.
FAQs & Answers
- Why does a leap year have 52 weeks and 2 extra days? A leap year has 366 days, which equals 52 full weeks (52 x 7 = 364 days) plus 2 extra days, making the calendar shift by two days each leap year.
- How is the probability of 53 Sundays in a leap year calculated? Since the 2 extra days can be any consecutive pair, and Sunday must be one of them to have 53 Sundays, the probability is 2 out of 7, or 2/7.
- Can the number of Sundays in a leap year be less than 52? No, a leap year always has at least 52 Sundays because there are 52 full weeks, so the minimum count of any weekday is 52.