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May 4th, 2017, 12:49 AM   #1
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number of elements

Let S be the sample space of days in a year (1,2,3...365). You have r number of people whose birthday you record (Example: {1,14,65,234....}). Let E be the event that the first person chosen has a birthday on day 3 and F be the event that the second person chosen has a birthday on day 28. Count the number of elements for {E}, {F}, {E and F}, and {E or F} ????

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Last edited by skipjack; May 4th, 2017 at 02:08 AM.
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May 4th, 2017, 01:01 AM   #2
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have you made any attempt at this?
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May 4th, 2017, 10:14 PM   #3
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Yes, I found the number of elements in E (n(E)) and f (n(F)). n(E) = n(F) =365^r-1. The number of elements in E and F ( n(E ∩ F) ) = 365^r-2. I think E or F (n(E ∪ F)) would be
n(E)+n(F)-n(E ∩ F), but I don't know if this is correct.

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