hi can you please help me I have a few questions but this one is important

The quoted mean number of milligrams of sodium in a certain brand of low-salt microwave frozen dinners is 670mg. A random sample of 46 dinners is selected and found to have a mean of 685mg and standard deviation is 29mg.
a. Using the sample statistics, find a 90% confidence interval estimate of the true population mean number of milligrams of sodium in this brand of low-salt microwave frozen dinners.


I don't know how to work it out, and am getting confused with what formula to use.

help would be great please.

I will show you how to do this one. That way you will know how to do others. OK?

To find the maximum error of estimate, use the formula

Look up the z score for a 90% CI. It is 1.645.



Add this to and subtract from the sample mean







With 90% confidence, we can say that the mean sodium content of all dinners is between

677.97 and 692.03

That's all there is to it. OK now?

Thank you so much I have Been stressing all might about this I'll try the other questions and see how I go.
Again, thank you :-)