Originally Posted by

**Selena** Can someone please help me with this question? I *think* my logic is correct but I always get the wrong final answer. =/

Question: Given the following information concerning how many days a person has to wait for a repair:

(# of days, probability)

(1, 0.10) *means 10% chance to wait 1 day*

(2, 0.25)

(3, 0.30)

(4, 0.25)

(5, 0.10)

A random sample of 5 customers selected, what is the probability that **at least** 4 people will have to wait **more than** 3 days?

I was trying to solve it by adding the probability of 4 people waiting more than 3 days to 5 people waiting more than 3 days, in other words P(4 people, day = 4, 5) + P(5 people, day = 4, 5) = [(5 select 4)(0.25 + 0.10)^4(1 - 0.25 - 0.10)^1] + [(5 select 5)(0.25 + 0.10)^5(1 - 0.25 - 0.10)^0], but that answer is wrong.

(sorry I'm not sure how to post those math symbols in picture format)

Can someone please enlighten me on this, thanks!