Answer to Question #98388 in Statistics and Probability for debra gross

Question

A recent survey found that 80% of all people over 60 years of age in a large city wear glasses. a random sample of 6 people over 60years of age is selected.

a. what is the probability that exactly 4 people will wear glasses?
b. what is the probability that at most 5 people will wear glasses?

Answer 1

That is the binomial distribution

P( 4 people from 6 wear glasses ) = C(6, 4) * 0.8⁴ * 0.2² = 0.245

P( at most 5 from 6 wear glasses ) = 1 - P(6 people from 6 wear glasses ) = 1 - 0.8⁶ = 0.737

where C(n, k) is the binomial coefficient.

Answer:

a) 0.245

b) 0.737