Question

A research team conducted a study showing that approximately 20% of all businessmen who wear ties wear them so tightly that they actually reduce blood flow to the brain, diminishing cerebral functions. At a board meeting of 15 businessmen, all of whom wear ties, what are the following probabilities? (Round your answers to three decimal places.) (a) at least one tie is too tight Correct: Your answer is correct. (b) more than two ties are too tight. (c) no tie is too tight (d) at least 13 ties are not too tight

Answer 1

Given that

Probability of businessmen wearing ties too tight =p=0.2

number of businessmen =n=15

let X is number of businessmen out of 15 who wearing ties too tight

so

a)

we have to find P(X>1)

now

=1-0.035=0.965

b)

we have to find P(X>2)
now

=1-0.398 =0.602

c)

we have to find P(X=0)

now

d)

we have to find P(X>13)

now

<0.001