00:01
So in question one in item a, we should compute what is the probability that the first marble here, so the first one will be red and the second one will be blue.
00:21
And we are considering that inside the box here we have eight reds, five whites, and nine blues.
00:37
This means that in total, like we have a total of 22 marbles here.
00:43
And we are only selecting two.
00:47
So now this means without replacement, this means that when you select the first one, you're not going to put like the ball or the marble in the box again, inside the box.
00:58
So basically, the probability of like getting the first one red is the amount that we have in red at the moment in the box in relation to the total number of marbles in the box.
01:12
So in this case, will be 8 divided by 22.
01:16
But then i'm also computing that the second one is blue.
01:22
So the second one in this case here to be blue is the same thing.
01:27
We have nine blue, so nine.
01:29
But now because i already select one marble that is what was red, i don't have 22 anymore.
01:34
I only have 21.
01:37
So this here will give us 0 .156 as the answer.
01:43
For item b, what is the probability that both of the same color, like the two marbles? so we could have red and red, we could have blue and blue, or we could have white and white.
02:00
So here we're going to use the same idea.
02:01
For this first one here, we have at the beginning, eight red out of 22 but then because i select already one red i only have seven and because i select the red i don't have 22 anymore i have 21 then this or here we're going to put plus then we compute this one so for the blue here we start with nine out of 22 then to select again another blue i have eight out of 21.
02:37
For the white, i have five whites at the beginning, then four out of 21.
02:45
So here we are going to get this probability 0 .32 .03.
02:53
Now for item c, what is the probability that the second one is red? so basically the first one could be anything, could be like a black or like, no, blue, then red.
03:12
I could have red and red or i could have white and red...