Aliens have invaded Planet Earth and are out to get us all T

Aliens have invaded Planet Earth and are out to get us all. The Avengers have been called to action, but there is a problem. Iron Man is still working on his suit. Thor is off to honeymoon with Natalie Portman. Captain America is down with flu, the Black Widow is currently spending time on Match.com and comparing results with eHarmony.com, and the other guy\'s how and arrows are under repair. Only Hulk remains. And a geneticist. The geneticist releases a virus to kill those nasty aliens. However the probability that a virus will kill an alien is only 0.5. Unfortunately also, while Hulk is, well, Hulk, he cannot handle more than 4500 aliens, and there are 10,000 of them. After all, aliens are also aliens and will not go down easily, as those great warriors, will Smith and Tom cruise found out. What is the probability that Hulk will be able to single handedly protect the planet?

Solution

Here we have to find out what is the probability that Hulk will be able to single handedly protect the plant. so we no need to consider other data. Since the hulk can handle only 4500 aliens, probability of him saving the planet is 4500/10000 =0.45.