its not only binomial... its full on MIXTURE of mathz!!!
wel... tried to differentiate tat last question...(since it's like 3marks) but didn't seems to get the write one~~
I believe thats right (unless proven wrong). I ended up doing (p+q)^7 expanded it out and it worked it out to be 1-q^7 where q=9/10 which is prob that she wouldnt win.
u expanded it? y not do binomial theorem it comes out quicker...
also last question, yeah i got to the last part, then i sorta fudged it to make it work...
hopefully ill only lose 1 mark for the fudge