A certain red blood disease affects 0.02% of the population.if the population is 1000,what is the probability that at most 5 people have blood disease?

Question

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Answer 1

This sounds like a binomial problem

 

At most 5 means 5 or less, 0,1,2,3,4,5

 

P(5) = 1000C5(.0002)^5(.9998)^995 +

 

P(4) = 1000C4(.0002)^4(.9998)^996 +

 

P(3) = 1000C3(.0002)^3(.9998)^997 +

 

P(2) = 1000C2(.0002)^2(.9998)^998 +

 

P(1) = 1000C1(.0002)^1(.9998)^999 +

 

P(0) = 1000C0(.0002)^0(.9998)^1000 

 

Add up all these individual probabilities

 

You can also use binomialcdf(1000,.0002,5)  in a ti calculator

or in excel

 

=BINOM.DIST(5,1000,0.0002,TRUE)

 

.9999999261

The 1000 most likely is a sample of 1000 people from the population