Stat question check please!

Question

Suppose the probability that a person with an average credit rating will pay a bill on time is 0.82. If 10 bills are sent out to a random sample of people with an average credit rating, what is the probability that exactly 8 of the 10 bills will be paid on time? (Express answer correct to 4 decimal places) .

I got ₁₀C₈ (.82)⁸(.18)^10-8= 0.2980 from the binomial prob. distribution equation. Is 0.2980 correct?

Answer 1

Yes; note that you can check the answer by using a calculator's statistics functions or Excel.

For example, in Excel, we can calculate using =BINOM.DIST(8,10,0.82,0) - the final 0 means exactly 8, not <= 8 (the probability mass function, not the probability distribution function).