SOLUTION: Question: A battery is defective with probability 0.3. What is the probability that in a pack of 8 batteries: 1) Exactly 2 are defective 2) At most 2 are defective? (hintL a

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Question 472041: Question: A battery is defective with probability 0.3. What is the probability that in a pack of 8 batteries:
1) Exactly 2 are defective
2) At most 2 are defective? (hintL at most = less than or equal to)
3) More than 2 are defective?
4) What is the expected number of defective batteries in the 8-pack?
5) What is the standard deviation of the number of defective batteries in the 8-pack?
Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
n=8, p=.3, q=.7
.
4)E(x)=np=8*.3=2.4
.
5)sigma=sqrt%28npq%29=sqrt%288%2A.3%2A.7%29=1.296
.
1)
nCr=8C2=28 coefficient
28*p^2*q^6=.2965
.
Ed