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∙ 12y agoP( 2 equal birthday in group of 15 ) ≈ 22.3%
The probability that 2 persons and only 2 persons in a random group of n persons can be calculated using the following expression*:
P(2 equal bd in group of n persons) = nC2(1-1/1461)(4/1461)Π2n-1[1-4(i-1)/1461] + nC2(1/1461)2Π2n-1[1-(4i-3)/1461]
with n=15, 30C2 = 105,
P(2 eq bd in group of 15) = 105(1-1/1461)(4/1461)[1-4/1461]
[1-8/1461][1-12/1461]∙∙∙[1-52/1461]
P(...) = 0.223263549... ≈ 22.3%
*You find this expression discussed in question "What is the probability that in a room of 8 people 2 have the same birthday ?". A simpler form of this expression that neglects February 29 of the leap day that gives a good
approximation is:
P(2 eq bd in group of n persons) = nC2(1/365)Π1n-1[1-(i-1)/365]
for n=15, this expression gives P(...) = 0.214918798... ≈ 21.5%
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∙ 12y agoThe probability of choosing 2 girls at random from group of 25 students of which10 are girls and 15 are boys is:P( 2 girls) = (10/25)∙(9/24) = 3/20 = 0.15 = 15%
I am not going to help you cheat in math class!!!!!!!!!!!!!
15/125 = 0.12
this is 15/91
The probability is 4/15
The ratio of girls to total students is 15:25, or 3:5. Three out of five students are girls so there would be a 60% probability that a girl would be chosen; a 2 out of 5 chance, or 40% probability that a boy would be chosen.
The probability is 15/25 = 3/5
To determine the probability of 15 random people all having the same birthday, consider each person one at a time. (This is for the non leap-year case.)The probability of any person having any birthday is 365 in 365, or 1.The probability of any other person having that same birthday is 1 in 365, or 0.00274.The probability, then, of 15 random people having the same birthday is the product of these probabilities, or 0.0027414 times 1, or 1.34x10-36.Note: This answer assumes also that the distribution of birthdays for a large group of people in uniformly random over the 365 days of the year. That is probably not actually true. There are several non-random points of conception, some of which are spring, Valentine's day, and Christmas, depending of culture and religion. That makes the point of birth, nine months later, also be non-uniform, so that can skew the results.
The probability is 15/25 = 3/5
The probability of choosing 2 girls at random from group of 25 students of which10 are girls and 15 are boys is:P( 2 girls) = (10/25)∙(9/24) = 3/20 = 0.15 = 15%
yes they have the same birthday. they were both born on December 15.
This is the same as the probability of choosing either a red of a blue marble. There are 5+4 out of 15 ways of doing this. The probability is therefore 9/15 = 3/5.
It is a probability; probability of side effect is .15 and probability of no side effect is .85.
December 15th 1986 is Max's birthday. Yes its the same as Ronnies
I am not going to help you cheat in math class!!!!!!!!!!!!!
15/125 = 0.12
August 12Her birthday is the 12th of August, which is the same as her older sister, Christina. Lauren will be 15 this year.