#1
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basic probability question
Could someone just tell me to about solving this question:
A saleswoman normally visits 60 homes in a week. She has a 20% chance of making a sale (indepent events) If the woman was to only visit 12 homes, what is the probability of her making more than 6 sales? Cheers, |
#2
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Re: basic probability question
This is a binomial distribution with p=20% , q=80% .
p=success q=failure Let x be a random variable of making a sale . P(x=7) = 12c7(0.2)^7*(0.8)^5 There are 12 choose 7 ways of making 7 successful sales from 12 homes selected . Similarly P(x=8) =12c8(0.2)^8(0.8)^4 Continue in this manner by adding P(x=7)+P(x=8)+P(x=9) +P(x=10) +P(x=11) + P(x=12) which is equivalent to P(x>6) The formula is P(X=x) = nCx*P^x*q^(n-x) , n=12 in this case |
#3
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Re: basic probability question
Cheers,
I was always taught that the formula for binomial distribution was; P(X=x) = (nCi)x(p^i)x(1-p)^n-i Think I like your more condensed 1 tho.. cheers |
#4
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Re: basic probability question
[ QUOTE ]
This is a binomial distribution with p=20% , q=80% . p=success q=failure Let x be a random variable of making a sale . P(x=7) = 12c7(0.2)^7*(0.8)^5 There are 12 choose 7 ways of making 7 successful sales from 12 homes selected . Similarly P(x=8) =12c8(0.2)^8(0.8)^4 Continue in this manner by adding P(x=7)+P(x=8)+P(x=9) +P(x=10) +P(x=11) + P(x=12) which is equivalent to P(x>6) The formula is P(X=x) = nCx*P^x*q^(n-x) , n=12 in this case [/ QUOTE ] This is 1 minus the probability of 6 or less, and in Excel you can use the function =BINOMDIST to do this sum for you as: =1-BINOMDIST(6,12,0.2,true) =~ 0.39% |
#5
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Re: basic probability question
cheers for that as well, i'll be needing that next semester.. in a few weeks time.lista
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