One out of every 5000 individuals in a population carries a certain defective gene. A random sample of 1000 individuals is studied.
a. What is the probability that exactly one of the sample individuals carries the gene?
b. What is the probability that none of the sample individuals carries the gene?
c. What is the probability that more than two of the sample individuals carry the gene?
d. What is the mean of the number of sample individuals that carry the gene?
e. What is the standard deviation of the number of sample individuals that carry the gene?
Solution
Step 1 of 6
Here given one out of every 5000 individual in a population carries a certain defective gene
So, p=1/5000
=0.0002
The sample size 1000
So, n=1000
Let X is no.of individuals carries the gene
Here XB(1000,0.0002)
Since ‘n’ is large and ‘p’ is small
The Binomial distribution will be converted to poisson distribution
The pmf of poisson distribution is P(X)=, X=0,1,2,..............
So, =np
=1000(0.0002)
=0.2
Hence XPoisson (0.2)