SOLUTION: Suppose that 25% of all people have teeth that are abnormally sensitive to heat, cold or touch. If we randomly choose 12 people, (a) What is the probability that none of them have

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Question 1105071: Suppose that 25% of all people have teeth that are abnormally sensitive to heat, cold or touch. If we randomly choose 12 people,
(a) What is the probability that none of them have abnormally sensitive to teeth?
(b) What is the probability that 10 or more had abnormally sensitive teeth?
(c) What is the expected number with abnormally sensitive teeth?

Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
a. 0.75^12=0.0317
b. From the calculator, probability is 0.9999 that 9 or fewer have
For 10, 66*0.25^10*0.75^2=0.000035
For 11 it is 12*.25^11*.75=0.000002
c. E(x)=x*p(x)=12*0.25=3