there are 7 boys and 6 girls willing to serve on a committee. how many 7-member committees are possible if a committee is to contain:

a) 3 boys and 4 girls

b) at least one member of each sex?

thank in advance!!

3 answers

a) What is C(7,3) x C(6,4) ?

b) with no restriction --- C(13,7)
all girls = C(6,4)
all boys = C(7,3)

exclude the all boys/girs from the total.
i did them but i got the wrong answers

for (a), the answer must be 525 and
for (b), the answer must be 1715

i got the rite answer for letter b though, by doing my own method
oh and thanks :]