.
Either use the formula to calculate each probability or use technology.
All formula can be found here if, for example, your dog ate the page of your notes that had them: Binomial distribution - Wikipedia, the free encyclopedia
It is believed that 20% of Americans do not have any health insurance. Suppose this is true and let X equal the number with no health insurance in a random sample of 15 Americans.
How is X distributed? I think its b(15,.20)
What is the mean, variance and standard deviation of X?
What is P(X 5)?
.
Either use the formula to calculate each probability or use technology.
All formula can be found here if, for example, your dog ate the page of your notes that had them: Binomial distribution - Wikipedia, the free encyclopedia
so SD= radical 2.4
for P(X 5):
1-[P(X=4)+P(X=3)+P(X=2)+P(X=1)+P(X=0)]=1-(4*1/5+3*1/5+2*1/5+1*1/5+0*1/5)=1-(4/5+3/5+2/5+1/5+0)=1
My answer doesn't seem correct. I feel like I should have included the probability of HAVING health insurance for the remaining.... for example, for X=4 there is an 80% chance for each of the the remaining 11 (15-4) to have insurance.
You have not correctly used the formula I gave you for calculating the probabilities. Please show all your working for how you calculated Pr(X = 1), say, so that what you're doing wrong can be pointed out.
By the way: You should realise that 4/5+3/5+2/5+1/5+0 adds up to more than 1, which is clearly absurd. This should have told you that your numerical calculations were wrong.