Question

of the physics graduates of a university, 35% received a starting salary of $50,000 or more. If 5 of the graduates are selected at random, find the probability that all had a starting salary of $50,000 or more.

Answer 1

Assume that there is an infinite number (or a large number) of physics graduates so that selecting 5 has negligible effect on the pool, then the proportion of well-paid graduates remains at 35%.
Then the probability for selecting one well-paid graduate is 0.35, and selecting 5 is 0.35^5=0.0053