00:01
Flair is hitting a pinata.
00:03
So the probability of getting the pinata on the first hit is 0 .6.
00:08
And then she's just going to keep hitting it with greater force each time.
00:12
So we're going to start by making the probability distribution or the first four swings.
00:20
So if she could get it first try.
00:24
The probability there would just be 0 .6.
00:29
We've been told probability she gets it first hit is 0 .6.
00:33
What's the probability she breaks it? on the second hit.
00:36
So it's not 0 .7 here because this requires that she failed to break it on the first hit.
00:45
So 0 .4 for failing on the first one and then 0 .7 for breaking it on the second.
00:54
So it's 0 .28.
00:59
On the third hip means she didn't break it on the second with 0 .3.
01:04
And then for the third hit, she's hitting it even harder, so that's 0 .8.
01:12
So we've got 0 .12 times 0 .8 is 0 .96.
01:23
For the fourth hit, so she fails on the third with probability 0 .2.
01:31
And then finally she has 0 .9 for hitting it on the fourth, which combined is 0 .0 .0 .2.
01:47
So that's the probabilities for the first four hits.
01:53
So 0 .6, 0 .7, 8, 9 .9.
01:55
Okay, perfect.
01:58
Let's have a look.
02:03
So now we want the expected value here.
02:13
We've only got the first four hits here.
02:15
So we don't actually have a complete probability distribution yet because a probability distribution has to add up total of 1.
02:23
So this is part a.
02:24
I'm going to add this for the fifth hit, and since at this point the probability of hitting with piniata has gone up to 1, because it's been going up from 0 .6 to 0 .7, 0 .9, that was 1.
02:41
So this has to be the rest of the probability, which is 0 .024.
02:49
So i'm just keeping that.
02:51
Now let's look at part b...