Prodigy, I interpreted that question to mean, "3 AVERAGE people".
So if you have someone that weighs 150 pounds, and a person that weighs twice as much and a person that weighs half as much, the answer is that the branch can not support those three people.
150 X 3 = 450 lbs., which is the maximum weight the branch can support.
150 + 300 (i.e. 150 X 2) + 75 (i.e. 150 / 2) > 450, thus the answer is false.
Is it weird that that question only took me like 3 seconds to figure out when I was taking the test? :p But those ones where like "a gork is better than a bonkly and a burz is worse than a popo. Is a popo better than a phuz?" questions, I don't have any flippin' idea, even after wasting precious minutes on them, so I just guess.