Answer:
147/572
Step-by-step explanation:
The number of combinations of n things chosen r at a time is
[tex]\binom{n}{r}=\frac{n!}{r!(n-r)!}[/tex] (Some writers use the symbol [tex]_nC_r[/tex])
Choose 4 women from the 7:
[tex]\binom{7}{4}=\frac{7!}{4!(7-4)!}=35[/tex] ways
Choose 3 men from 9:
[tex]\binom{9}{3}=\frac{9!}{3!(9-3)!}=84[/tex] ways
There are 35 x 84 = 2940 ways to choose both, out of
[tex]\binom{16}{7}=\frac{16!}{7!(16-7)!}=11440[/tex] ways to choose any 7 people from the group of 16.
Probability:
[tex]\frac{2940}{11440}=\frac{147}{572}[/tex]
P.S. As an example of how to calculate combinations, here's the calculation (by hand, a calculator is easier!) of [tex]\binom{9}{3}[/tex].
[tex]\binom{9}{3}=\frac{9!}{3!(9-3)!}=\frac{9!}{3!6!}[/tex]
When you write out the factorials, you can do a bunch of cancellation between the numerator and denominator.
[tex]\frac{9\cdot8\cdot7\cdot\cancel{6\cdot5\cdot4\cdot3\cdot2\cdot1}}{(3\cdot2\cdot1)(\cancel{6\cdot5\cdot4\cdot3\cdot2\cdot1)}}=\frac{9\cdot8\cdot7}{3\cdot2\cdot1}=84[/tex]
