PROBABILITY

Question

An urn contains pink and green balls. Five balls are randomly drawn from the urn in succession, with replacement. That is, after each draw, the selected ball is returned to the urn. What is the probability that all balls drawn from the urn are pink

Answer 1

if there are p pink balls and g green balls

the probability of drawing randomly 5 pink balls, with replacement is

(p/(p+g))^5

probability without replacement is

(p/(p+g))((p-1)/(p+g-1))(p-2)/(p+g-2))((p-3)/(p+g-3))((p-4)/(p+g-4))((p-5)/(p+g-5)