00:01
Hi, i'm david and i'm here to have you answer your question.
00:04
Now let me bring up your question here.
00:07
In this question here we're going to discuss about the common interval.
00:11
Let me remind you that the company interval for the sample mean it will be the x bar plus or minus z n4 over 2, tangle the sigma over square to n.
00:24
In this quantity here, the one on the right, it will be called the margin error.
00:30
Now in this question here we are given that when to find the 90 % competent within the 3 of the 2 average.
00:40
It means that the matching error want to have equal to the 3.
00:47
And then we will have the standard division sigma it will equal to the 14.
00:54
And from here we want to find the n here.
00:59
Now we look at the formula we see we need to find the z npha over 2 and the 90 % common interval.
01:07
We know that the nphal equal to the 10 % and 4 over 2 equal to the 5%...