SOLUTION: Out of 2 million hay fever sufferers, 20% are allergic to tree pollen. If 11 hay fever victims are picked at random what is the probability that 5 have tree pollen what is the prob

Question 258127: Out of 2 million hay fever sufferers, 20% are allergic to tree pollen. If 11 hay fever victims are picked at random what is the probability that 5 have tree pollen what is the probability that 7 have tree pollen,what is the probability that none have tree pollen allergy and what is the probabiltiy that at least one has tree pollen allergy? Any help with this would be greatly appreciated.
Thanks Susan
Answer by edjones(8007) (Show Source): You can put this solution on YOUR website!
This is a binomial expansion.
t=tree pollen allergy, n=no tree pollen allergy
Let t=.2 and n=.8
(n+t)^11
.
none have tree pollen allergy: n^11=.8^11=.0859
.
the probabiltiy that at least one has tree pollen allergy: 1-.0859=.9141
.
the probability that 5 have tree pollen allergy: nCr=11C5=462 the coefficient.
462*n^6t^5=462*.8^6*.2^5=.0388
.
the probability that 7 have tree pollen: 11C7=330 coefficient
330*n^4t^7=330*.8^4*.2^7=.0017
.
Ed
RELATED QUESTIONS
About 11% of the population is allergic to pollen. If two people are randomly selected,... (answered by ewatrrr)

About 18% of the population is allergic to pollen. If two people are randomly selected,... (answered by stanbon)

about 6% of the population is allergic to pollen. If two people are randomly selected,... (answered by reviewermath)

9% of the population is allergic to pollen. If two people are selected randomly what is... (answered by amoresroy,Alan3354)

about 15% of the population of a large country is allergic to pollen if two people are... (answered by oscargut)

hay (answered by Alan3354)

Margaret ran out of hay to feed her horses and needs to but enough to last until a new... (answered by richwmiller)

A farmer, Sarah, has 54 hectares of hay to harvest, she hires a harvester at �1200 a day. (answered by Theo)

Jay stores hay in cubic stacks on his farm. If the length of each stack is 2/3 yard, what (answered by rfer)