00:01
So this is question 42.
00:02
And in question 41, you had to find a 95 % confidence interval.
00:08
And so you were taking the x bar that was obtained, which was 1 .5 hours.
00:15
And then plus or minus.
00:18
And if we're to assume a normal population, then we're going to be using the 95 % competence interval number will be 1 .96.
00:26
And then we're going to use our sample size.
00:28
And again, we could use a t star value here if we weren't assuming a normal distribution, but with 69 degrees of freedom.
00:38
But if we use that, and then we had the standard deviation of the sample, which was 0 .5 hours, and then divided by the square root of 70.
00:48
And so you obtain this being our margin of air.
00:52
And again, this is from question 41.
00:54
And you get an interval.
00:57
That's going to end up being as low as, let's see, if we take 1 .5 minus the 1 .96 minus, excuse me, times.
01:08
0 .5 divided by the square root of 70...