# Margin of Error of a Confidence Interval

#### annehenderson

##### New Member
Hey all,
So I have a question that asks to find the margin of error from a confidence interval for a population mean, the confidence interval has a length of 162.6.
The only way I can find to obtain the margin of error is with zalpha/2 x standard deviation/ square root of n and I don't have any of that information. Can someone explain to me how to figure out this problem? I feel like it's really simple but I can't for the life of me figure this out! My textbook and professors notes aren't really clearing things up.
Thank you!

#### Dason

If you did have that information what would you do with it to create a confidence interval?

#### annehenderson

##### New Member
to create a confidence interval you add and subtract the x-bar with the margin of error, correct?

#### Dason

Using that - how long is a confidence interval?

#### annehenderson

##### New Member
my confidence interval is 162.6, so would i add and subtract 2.4 to it and that would be my margin of error? (i got the 2.4 from textbook, there was a little blurb on using 2.4 to creat margins of error) that's kind of the only thing i can think of since the length of my confidence interval is the only information given, unless i'm just totally missing the point.