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# Ask the Professor Forum

Hi professor. On the mixed review for chapter 2, number 64 has confused me. For summation notation, I have no problem figuring out the problems and the steps when given a set of numbers, but number 64) almost has us work this back words without a given set. Is this what the question will look like on the exam instead of what was shown in class? Could you give me a hint on how to start this problem...

Posted to STATS 1 on Sunday, September 21, 2014   Replies: 2

Professor Mcguckian
09/21/2014
3:50 PM EST

Hi Reina,

I think you might be overlooking the directions for this problem. This is not a summation notation problem. The problem asks, "Calculate the standard deviation for a set of 12 values that have the following summary values...." If you look at the formula for standard deviation, you will see that you have everything you need to solve this problem.

There were several problems in the homework just like this one, except in those I also gave the actual data values (which are unnecessary).

Hope that helps,

Professor McGuckian

.
09/21/2014
4:22 PM EST
Wow, my apologies! I've been looking at math problems for to long to have made that mistake! Your absolutely right, that helped. I immediately assumed that was a summation notation. Problem solved :)