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May 3rd, 2017, 11:49 PM  #1 
Newbie Joined: May 2017 From: phoenix, az Posts: 7 Thanks: 0  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} ???? Thanks Last edited by skipjack; May 4th, 2017 at 01:08 AM. 
May 4th, 2017, 12:01 AM  #2 
Senior Member Joined: Sep 2015 From: USA Posts: 1,974 Thanks: 1026 
have you made any attempt at this?

May 4th, 2017, 09:14 PM  #3 
Newbie Joined: May 2017 From: phoenix, az Posts: 7 Thanks: 0 
Yes, I found the number of elements in E (n(E)) and f (n(F)). n(E) = n(F) =365^r1. The number of elements in E and F ( n(E ∩ F) ) = 365^r2. 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. Thanks 

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