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Tshiamogetse
Oct 18, 2010, 09:50 AM
What is the probability of being born on:
a) the 10th of a month in a non-leap year
b) christmas day in a non-leap year
c) the 29th February

Unknown008
Oct 18, 2010, 09:58 AM
a) First, you need to be born on a non-leap year. What is this probability?
Then, you need to find the probability of being born on a 10th. How many 10th's are there in the number of non-leap years you chose in your probability?
Multiply those together to find the combined probability.

Can you try out the two others using the same principle?

ebaines
Oct 18, 2010, 10:53 AM
I think (a) is a little simpler than what Unknown008 laid out. I believe what the OP means to ask is: if you are born in a non-leap year, what's the probability of being born on the 10th day of a month? To do this, first consider: how many 10th days of a month occur in a year? Second, how many days are in a non-leap year? Then divide the first by the second.

As for (c) - it could get a bit complicated, unless you make an assumption that leap years occur every 4th year. Feb 29 comes around once every 4 years, and the number of days in 4 years is 4 x 365 + 1 for the leap year. However, to truly get this right you should consider that in each span of 400 years there are three "missing" leap years - namely in those years that are divisible by 100 but not divisible by 400. Thus 1900 was not a leap year, but 2000 was. So over the course of 400 years there are 97 leap years, and the number of days in 400 years is 400 x 365 + 97.