- #1
tsukuba
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Homework Statement
Each student who enters Professor James Moriarty's office has a 10% chance of being
manipulated into participating in some criminal scheme. Assume that Moriarty's classes are so
large that the students can be considered independent with regard to their meetings with him.
If 18 students visit Moriarty during his office hours, then the probability he will gain four or
more new criminal underlings is
Homework Equations
I am 100% sure this a binomial random variable.
the formula is:
p(x)= nCx * p^x * (1-p)^n-x
The Attempt at a Solution
so n=18
x=0,1,2,3
p=0.1
p(x=0)=0.15
p(x=1)=0.017
p(x=2)=1.85x10^-3
p(x=3)=2.06x10^-4
p(4 or more students)= 1- p(x=0) - p(x=1) - p(x=2) - p(x=3)
=0.831
The answer is 0.098