00:01
Tom fires two torpedoes at a ship.
00:02
Each torpedo independently has a one in three chance of hitting.
00:06
Okay, so the ship will sink if either torpedo hits it.
00:10
I'm going to give these torpedoes names, a and b.
00:13
So there are four possible outcomes here.
00:15
Maybe they both hit.
00:17
Maybe a hits but b doesn't.
00:19
Maybe a doesn't, b does.
00:21
Maybe neither of them do.
00:24
For the probabilities here, since they are independent, we can just combine the probabilities by multiplication.
00:30
So the probability they both hit is a third times a third, one in nine.
00:35
A is a third times two thirds, so that would be two in nine.
00:40
Also two in nine, this would be two thirds times two thirds, four over nine...