Question

A photography student took portrait photos of people from his hometown. He wants to

develop 21 of the photos, 9 of which were photos of babies.
If he randomly chooses to make 4 of the photos black and white, what is the probability that
all of them are of babies?

Answer 1

Answer: The total number of ways the photography student can choose 4 photos out of 21 is given by the combination formula:

Step-by-step explanation: C(21, 4) = (21!)/((4!)(21-4)!) = 5985

Out of the 21 photos, 9 were photos of babies. The number of ways the student can choose 4 baby photos out of 9 is given by:

C(9, 4) = (9!)/((4!)(9-4)!) = 126

Therefore, the probability that all 4 photos chosen are of babies is:

P = (number of ways to choose 4 baby photos)/(total number of ways to choose 4 photos)

P = C(9, 4)/C(21, 4)

P = 126/5985

P ≈ 0.021

So, the probability that all 4 photos chosen are of babies is approximately 0.021 or 2.1%.