00:01
Now here in this problem, we are going to be working with a few different probabilities, but the first thing that is very important to know is this property of random variables and that the sum of the probabilities must equal one.
00:13
Whenever you add up everything that is possible, they must all add together to one.
00:19
So here starting on part a.
00:22
We know that the probability that t is greater than 2 .02 .0 .05.
00:30
We know that the probability that t is less than negative 2 .02 is also 0 .05.
00:43
We want the probability that t is between those.
00:49
Now we've covered every possibility here.
00:52
T is either bigger than 2 .02, less than 2 .02, or it's in between the two.
00:59
And so we have everything covered here.
01:01
So what that means is that when we add these three together, and when we add the three of these together, that needs to equal 1.
01:23
Well, we know that greater than 2 .02 has a probability of 0 .05, plus the negative 0 .202 is another 0 .05.
01:34
So adding that together gives us 1...