00:01
A coffee machine dispenses coffee into paper cups.
00:03
You're supposed to get 10 ounces of coffee, but the amount varies slightly from cup to cup.
00:07
A random sample of 20 cups was selected, and the amount of coffee dispensed in each cup was measured.
00:12
We're given a histogram.
00:13
The distribution is approximately normal.
00:17
Part a, for one experimental unit, what's the response variable? and that would be our ounces of coffee dispensed.
00:30
And is that categorical or quantitative? that's going to be quantitative.
00:36
For part b, some of the things we want to think about for a t -test needs to be random, needs to be independent.
00:47
We know that it's approximately normal distribution.
00:53
So for c, conduct a significance test to determine if there is evidence that, on average, the machine is shortchanging customers.
01:00
Means our null hypothesis is that mu is equal to 10 versus the alternative that mu is less than 10.
01:06
So our t -test statistic is 9 .85 minus 10 divided by .20, divided in turn by the square root of 20.
01:16
And that is a test statistic of negative 3 .35, which has a p -value of .0033...