00:01
Hi, i'm david and i'm here to have you answering your question.
00:03
In the question here, we are going to discuss about the hypothesis testing.
00:07
Here, when you test the mean lifetime of a new life -up is less than the 500 hours.
00:13
It means then when you test the known hypothesis that the mean will be quite equal to the 500 versus the alternative hypothesis, then the mean will be less than the 500.
00:25
Notice that this will be the left -tale test.
00:28
And here we're given the symbol and it will equal to the 40.
00:36
And we're given the x -par, it will equal to the 492 and the s equal to the 18.
00:44
So from this information here, we will need to find the test statistics denoted by the z observed.
00:52
And it will equal to the x bar minus the mean over the s divided by square square.
00:59
And if we compute we have the 492 minus the mean will be the 500 then divided by the s going to be 18 over square into the end will be the 40 and if we compute we have 492 minus 500 divided by 18 times square in the 40 then we get equal to minus 2 .811 i see you can it correctly but technically this one we shouldn't we shouldn't put a z because we have the sigma is unknown, so we have to put this on as a t.
01:32
That would be more precise here...