statistics, find the probability
posted by troy on .
It is known that 77% of all new products introduced in grocery stores fail (are taken off the market) within 2 years. If a grocery store chain introduces 62 new products, find the following probabilities. (Round your answers to four decimal places.)
(d) within 2 years fewer than 10 succeed

prob(fewer than 10 succeed) > prob(none succeeds + one succeeds + 2 succeed + ...+ 9 succeed)
= (.77)^62 + C(62,1)(.23)(.77^61) + C(62,2)(.23^2)(.77^60) + ... + C(62,9)(.23^9)(.77^53)
= ....
lots of buttonpushing here 
When I computed this, it came out very oddly.. The C is throwing me off. cNr?

Yes
C(n,r) = _{n}C_{r}
= n!/(r!(nr)!)
e.g. C(62,2) = 62!/(2!60!) = 1891
most calculators have the _{n}C_{r} key, mine is the 2nd function of the 5 key
e.g. to find C(62,2)
enter:
62
_{n}C_{r}
2
=
to get 1891
PS. I did not take the time to find the final answer to the above string of probabilities.