00:01
All right, so we have a fair coin that's tossed eight times and the face that appears is recorded.
00:06
So we want to know how many elements of the sample space will have no tails.
00:15
So probability of getting no tails is just getting eight heads.
00:20
So we notice only one scenario where that happens.
00:26
For b, we want to know how many elements of the simple space will have exactly one tail.
00:35
So probability of or to get one tail, we have eight different spots.
00:41
So we need to just choose one.
00:44
So there's eight different scenarios where that would happen.
00:48
For c, we want to know how many elements of sample space start with a pair.
00:53
So either tells, tells, or heads, heads, or end with the pair, tells, tells, or heads heads.
00:58
And have a total of exactly two tails.
01:04
Right.
01:04
So either you start with, you can start with tells, tell, tells.
01:13
So then, and you want exactly two.
01:17
Tells so we're going to have different scenarios so you have start with tails tells then and you only have two tells during the number that we start with heads heads but we we only have exactly two tells and then we have another scenario where we end with tells tells and there's only two tells and then the last scenario of end with heads heads and there's still exactly two tails so if we start with tails tells then we're only left with six positions and we only have two tails so those have been taken up so it would just be two to six so if we start with heads heads and then have exactly two tails so we know the first two spots are taken up by heads so then the last six spots we need to just have two tails so we're gonna have six choose two so six choose two we're going to have 15 options there.
02:47
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