Question

A research team conducted a study showing that approximately 25% 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.)

(d) at least 13 ties are not too tight

Answer 1

Let , X be the number of businessmen who wear ties wear them so tightly.

Here ,

Therefore , the probability mass function of X is ,

; x=0,1,2,.........,n and q=1-p

= 0 ; otherwise

Now , first we want to find the probability that the at least 13 ties are too tight.

Therefore ,

Therefore , the probability that the at least 13 ties are not too tight=1-probability that the at least 13 ties are too tight

=1-0.0000