SOLUTION: It has been estimated that only about 30% of California residents have adequate earthquake supplies. Suppose you randomly survey 11 California residents. We are interested in the

Question 628548: It has been estimated that only about 30% of California residents have adequate earthquake
supplies. Suppose you randomly survey 11 California residents. We are interested in the
number who have adequate earthquake supplies.
d. What is the probability that at least 8 have adequate earthquake supplies?
e. Is it more likely that none or that all of the residents surveyed will have adequate earthquake
supplies? Why?
I tried to do this question by using Binomial Probability Distribution. I took my p as 0.3 and n=11. But it says at least 8 so the probability was P(x>=8) and when i calcualated i got some weird result . If anyone can and have time to do it i would appriciate thank you!
Answer by ewatrrr(24785) (Show Source): You can put this solution on YOUR website!

 

Hi,

30% of California residents have adequate earthquake supplies...survey 11 of them

P(x ≥ 8) = 11C8(.3)^8(.7)^3 + 11C9(.3)^9(.7)^2 + 11C10(.3)^10(.7)^1 + 11C11(.3)^11

Stattrek.com Bionomial Calculator gives  P(x ≥ 8) = .0043

e. Is it more likely that none or that all of the residents surveyed will have adequate earthquakesupplies? Why?

 None (only 30% have them)and ...  P(0)= .02 > P(11)= .0000018 

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