00:01
In this question, we are going to be completing a hypothesis test for the recommendation on oil changes.
00:09
So our null hypothesis here is what they actually recommend.
00:12
They recommend every 3 ,000 miles.
00:14
And we're going to see if the general population is outside of that.
00:22
So we are going to see if the oil change exceeds 3 ,000 miles.
00:27
So if it's greater than 3 ,000 miles.
00:29
So just like we've been doing, we're going to calculate our z score.
00:32
So we're going to take our sample mean 3752, subtract our expected mean, which would be everybody changes it just when they're supposed to.
00:41
Our standard deviation divided by the square root of our sample size of 50, which gives us a z score of 8 .33.
00:57
Whoa.
00:58
That's extremely high.
01:01
It's a one -tailed test.
01:02
So we're going to compare it with the z score at 0 .05...