According to the Canadian Journal of Information and Library

According to the Canadian Journal of Information and Library Science (Vol 33, 2009). the probability that workers in Canadian law libraries are satisfied with their job is 0.9. In a random sample of 12 law librarians in Canada, what is the probability that exactly 10 of them are satisfied with their job? Round answer to nearest ten-thousandth (4 places after decimal).

Solution

p=0.9

q =0.1

probability that exactly 10 out of 12 are satisfied with their job is ¹²c₁₀(0.9)¹⁰(0.1)²

=66*(0.9)¹⁰(0.1)²

=0.2301

probability that exactly 10 out of 12 are satisfied with their job is 0.2301