I am taking a guess. Like I saw this example (5/9)(4/8)(3/7)(2/6)=120/3024=0.0397
Or (5C4)/(9C4)=0.0397 - from chisnau
Follow those steps, but add your numbers . I added one zero bassed on the problem: There are 9 students in a class: 5 boys and 4 girls. If the teacher picks a group of 4 at random, what is the probability that everyone in the group is a boy?