birthday prob

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ruplun: Master | Next Rank: 500 Posts; Posts: 232; Joined: Fri Jun 18, 2010 7:09 amFollowed by: 2 members; Thanked: 1 times

by ruplun » Fri Jul 29, 2011 5:27 am

In a group of 8 persons what is the probability that at least 2 of them are born on the same day of the week?

a. 1/8
b. 1/7
c. 1/4
d. 1/2
e. 1

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Source: Beat The GMAT — Problem Solving | Fri Jul 29, 2011 5:27 am

naveen451: Senior | Next Rank: 100 Posts; Posts: 60; Joined: Sat Jul 16, 2011 11:56 pmFollowed by: 1 member; Location: hyderabad; Thanked: 2 times

by naveen451 » Fri Jul 29, 2011 9:17 am

IMO E

because there are only seven days a week

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ruplun: Master | Next Rank: 500 Posts; Posts: 232; Joined: Fri Jun 18, 2010 7:09 amFollowed by: 2 members; Thanked: 1 times

by ruplun » Fri Jul 29, 2011 9:04 pm

plz explain

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ntamhane: Senior | Next Rank: 100 Posts; Posts: 34; Joined: Thu Jun 30, 2011 4:15 amFollowed by: 1 member; Thanked: 1 times

by ntamhane » Fri Jul 29, 2011 9:40 pm

Mon Tue Wed Thrus Fri Sat Sun
P1 P2 P3 P4 P5 P6 P7
P8

If you try out any of such samples you will get minimum of 2 people born on the same day.

Hence Probability is 1 i.e E

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