How do you calculate the EXACT probability?

Question

I also want to know what the formula is and the steps in doing it , like an example please

Answer 1

The following video may be of assistance:

http://highered.mheducation.com/olcweb/cgi/pluginpop.cgi?it=swf::600::450::/sites/dl/free/0073386103/293152/ch5_sec4_part1.swf::5.3%20Part%201%20-%20Find%20exact%20binomial%20probability.