Mrs. Gomes found that 40% of students at her high school take chemistry. She randomly surveys 12 students. What is the probability that at most 4 students have taken chemistry? Round the answer to the nearest thousandth.

Question

A)0.008
B)0.438
C)0.562
D)0.665

Answer 1

Use the binomial distribution,
p=P(chemistry)=0.4
n=12 (sample size)
r=number taking chemistry

P(n,r)=nCr*0.4^r*(1-0.4)^(n-r)
where nCr=n!/((n-r)!r!) is binomial coefficient.

For probability of getting AT MOST 4 taking chemistry, add up all possible cases, i.e. 0,1,2,3,4, or
P(12,0)+P(12,1)+P(12,2)+P(12,3)+P(12,4)
the answer should match one of the choices.

Answer 2

0.004

Answer 3

I'm not even in this class. Lol.

Answer 4

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