00:02
Okay, with this problem, we're going to be thinking about a few different things.
00:07
We're going to be thinking about z scores, quartiles, intercortile range, and outliers.
00:14
And so the context is they give us some data showing the miles per gallon for a random sample of smart cars.
00:27
So here was the data that they gave us.
00:30
And the first thing they ask us to do is to compute the z score for a car that got 36 .3 miles per gallon.
00:44
So for this guy right here.
00:49
So remember a z score is the value itself minus the mean, divided by the same.
01:01
Standard deviation.
01:03
So i needed to find in order to work the problem, i needed to find the mean of the sample and the standard deviation.
01:13
So i put the data into my ti -84 calculator and calculated the one variable stats.
01:19
So i had the information i needed.
01:21
So i'm going to plug in the values 36 .3 minus the mean of 38 .775 divided by the standard deviation, 3 .416.
01:39
And let's go ahead and plug that in, 36 .3 minus 38 .775 divided by 3 .416.
01:50
Gives me a z score of negative 0 .775, gives me a z score of negative 0 .775, gives me a z score of negative so what this means, the interpretation would be that this smart car has an mpg that is 0 .725 standard deviations below the mean.
02:33
Average because it's below.
02:35
And notice when i interpreted it, the negative became below.
02:41
The second thing it asked us to do is to find the quartiles.
02:48
And actually, because i had used my calculator to find the mean and standard deviation, it also gave me the quartiles here.
02:58
Oops, and let me undo that because i have covered it up where i can't see it.
03:04
I also want the median.
03:07
So here's my q1 median, remember, is q2, and q3 is 41...