Disecrete Probability Distributions Help Needed?

I'm totally lost on the following problem, can anyone please help me out? Thank you in advance!





1. Survey conducted showed that the average commuter spends about 26 min on a one-way door-to-door trip. Also 5% of commuters reported a one-way commute of over an hour.





a. If 20 commuters are surveyed, what is the probability that three will report a one-way commute of more than one hour?


b. If a company has 2000 employees, what is the expected number of employees with a commute of more than one hour?

Disecrete Probability Distributions Help Needed?
Hi,





a. 20nCr3 (.05)^3(.95)^17 = .0595 = 5.95% probability





b. 5% of 2000 = 100





I hope that helps!! :-)