00:01
So i see that you need help with these few problems.
00:04
And i'm going to answer a and b.
00:07
I was able to find it better worded online.
00:11
So it says two balls are drawn in succession out of a box containing three red and four white balls.
00:17
Find the probability that at least one ball is red given the first ball was a replaced before the second draw.
00:25
So for a, the first thing that i would do is, okay, say, you pulled a white because only one of them needs to be, only one of them needs to be red.
00:39
So let's focus on the white first.
00:41
So three out of eight is red times three out of eight, which gives you nine out of 64.
00:47
And that's the probability of you getting white on each pick.
00:52
And then what you had to do was one whole of minus nine over 64.
01:00
Would get you 55 out of 64.
01:04
So that would be the probability of you picking at least one red.
01:15
Okay? so now for b, without replacement, so you would take what white the first time would be 3 out of 8 times, and then remember one of the white's missing, so now you only have a 2 out of a 7 chance.
01:30
So that's a 6 out of a 56 chance.
01:32
I'm going to simplify the fraction, and it's going to become three out of 28.
01:38
And so then i take my one hole, and i'm going to subtract the odds of the white, and i'm going to get 25 out of a 28 chance of you getting at least one red.
01:58
Now, if you need to change these to an integer, oh, it says an integer or a fraction, so you can pick either one of those.
02:07
All right, so now for this next one, a box contains two red, three white, and four green balls.
02:13
Two balls are drawn out of succession without replacement.
02:16
What is the probability both balls are the same colors? all right, so you have your red balls, and i'm just going to call red one, red two, red three, and red four.
02:30
Then you have your white balls...