#### italiarep

##### New Member
i've created a chart using excel and i need it to derive the Z alpha/2 value from the table which i have input into the excel sheet. I want to be able to input the Confidence Interval and automattically have it Divide that number by 2 then divide it by 100 and then look up the closest value in the table. How can this be done, any advice would really help me out, this is for a Business Statistics class, the teacher challanged me to do it and i've been trying to figure it out.

Here is a link to my file so you can get a gist of what i'm trying to do http://www.microwholesale.com/comm/ProblemSolver.zip

### Excel Facts

Get help while writing formula
Click the italics "fx" icon to the left of the formula bar to open the Functions Arguments dialog. Help is displayed for each argument.
look a the confidence interval and the z alpha/2 portion of it. the formula is as follows.

(x1-x2) +- z alpha/2 Sqrt s1^2/n1 + s2^2/n2

the z alpha/2 is derived by taking that number dividing it by 2 then dividing that # by 100 and looking it up in the chart.

anybody?

anybody?

One reason why you may not be getting a response is because it is against board policy to do homework for students. But, that doesn't mean we can't still 'help' you.

Instead of asking how to do this, why don't you explain what you have tried, what your expected results are, etc. We can't give you the answer, but we can certainly help guide you and help you help yourself.

Also, you really haven't clearly defined which part your having problems with. Is it the looking up part, formula writing, charting...???

Ok, I took a look at your example and I see what you have tried. I assume your talking about looking up the value in A20:K56. But how do you know which column to return? Or are you just looking to return the closest match in column A? If that's the case then:-

=LOOKUP((B7/2)/100,A22:A56)

may be what your looking for.

Post back and let me know.

There is no need to create a table and look up values in it.

XL supports a variety of statistics functions. Look up Normal, NormInv, TDist, Tinv as well as the broader category of 'List of worksheet functions (by category)' It's unfortunate that the newer versions of XL (Office?) make it increasingly harder to find useful information in help, but it is there if you persevere.
italiarep said:
i've created a chart using excel and i need it to derive the Z alpha/2 value from the table which i have input into the excel sheet. I want to be able to input the Confidence Interval and automattically have it Divide that number by 2 then divide it by 100 and then look up the closest value in the table. How can this be done, any advice would really help me out, this is for a Business Statistics class, the teacher challanged me to do it and i've been trying to figure it out.

Here is a link to my file so you can get a gist of what i'm trying to do http://www.microwholesale.com/comm/ProblemSolver.zip

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