i. Determine the number of ways in which the committee may be
formed if it is to contain exactly one women.
Choose the 1 woman any of C(4,1)=4 ways.
Choose the 3 men any of C(8,3)=56
Answer: 

ii. Find the probability that at least one women is selected onto the
committee.
We find the probability that no women (i.e., all men) are chosen, then
subtract from 1.
Number of ways to select all men: C(8,4)=70 ways
Number of ways to select any 4 people regardless of sex: C(12,4)=495 ways.
P(all men) = 70/495 = 14/99
P(at least one woman) = 1-14/99 = 99/99-14/99 = 85/99.
Edwin