31% of adults say that cashews are their favorite kind of nut. You randomly select 12 adults and ask them to name their favorite nut. Find the probability that the number who say cashew istheir favorite nut is a(exactly three) b. at least four and c at most 2

Answer 1

a. 12C3(.31)^3(.69)^9 = .23235

b. 1-[(12C0)(.31)^0(.69)^12 + 12C2(.31)^2(.69)^10 + 12C3(.31)^3(.69)^9 ] = 0.5381

c. 12C0(.31)^0 (.69)^12+ 12C1(.31)^1(.69)^11 + 12C2(.31)^2(.69)^10 = 0.2295875