Practice Room · Shared-birthday odds

Practice: Birthdays

For each question, give a low and a high you are 80% sure the answer sits between. Tighter brackets score more; a miss scores zero. You can type 2 million, 3e9, 1.5k or 45%.

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BirthdaysQuestion 1 of 5

30 people are in a room. Counting all 365 birthdays as equally likely (ignore February 29), what is the chance, in percent, that at least two of them share a birthday?

Low High percent

BirthdaysQuestion 2 of 5

58 people are in a room. Counting all 365 birthdays as equally likely (ignore February 29), what is the chance, in percent, that at least two of them share a birthday?

Low High percent

BirthdaysQuestion 3 of 5

39 people are in a room. Counting all 365 birthdays as equally likely (ignore February 29), what is the chance, in percent, that at least two of them share a birthday?

Low High percent

BirthdaysQuestion 4 of 5

59 people are in a room. Counting all 365 birthdays as equally likely (ignore February 29), what is the chance, in percent, that at least two of them share a birthday?

Low High percent

BirthdaysQuestion 5 of 5

9 people are in a room. Counting all 365 birthdays as equally likely (ignore February 29), what is the chance, in percent, that at least two of them share a birthday?

Low High percent

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