00:01
Okay, so here we have julia thinks that she has a special relationship with the number four.
00:04
So when she rolls a four -sided dice, she thinks that she gets a four more often than she's supposed to by chance.
00:09
There are six numbers on the dice, so our null hypothesis is going to be that the probability, or proportion of rolls is going to be one -sixth.
00:24
That she's going to roll it a sixth of the time.
00:27
And then our alternative hypothesis is going to be that p is greater than one -sixth.
00:34
So that's part a.
00:38
Then part b, we're going to actually do the hypothesis test.
00:43
So it says we're going to assume that she makes 42 rolls and she comes up with a four nine times.
00:59
So we're going to take nine divided by 42.
01:04
So we got that p is 0 .21.
01:09
I'll just round it to there, 0 .21.
01:11
So now we want to conduct our hypothesis test and see if this is going to be the case or not.
01:19
So the first thing that i want to do is just choose a confidence level and we'll just do 95 % because that's the most common.
01:30
And so i'll do the z -score negative 1 .96 and 1 .96.
01:36
These are just known values at a 95 % confidence level and it's also on your z -chart if you want to look it up.
01:44
Because we have a sample of at least 30, we can do a z -score.
01:50
So what i'm going to do is convert this into a z -score and this is going to be my p hat, my sample p.
01:55
So it's going to be 0 .21 minus 1 over 6 is 1 .17.
02:05
So i'm just going to write that here.
02:08
They wanted you to write it as a fraction but now when we're plugging it in we're going to have to put it as a decimal.
02:12
0 .17 over square root, it's going to be p...