Here's a Q&A that you should read, both to make one of the questions on 
HW2 easier to do, and to improve the chance that you'll get it right:

> Attached to this e-mail is a copy of the excel spread sheet that I
> made to answer the question from homework set #2 about information from
> the FRED page. I am sure there is a faster way to remove information from
> a downloaded data set, but I didn't know how to do it. I would be
> interested in knowing how you solved the problem with out removing data
> readings from the CPI and M1 data bases.

[The problem here is that M1 is reported monthly, while the other data are 
reported quarterly.  To get just the M1s wanted, this student had to do a 
lot of cut-and-pasting, or deleting, and this was cumbersome to do.]

I've looked at it, and also at my own solutions.  What I did was use the 
"vlookup" function, to look up just the M1s that I wanted.  That's really 
easy once you know about that function, which I imagine most people don't. 
Another somewhat harder way would be to add a column of integers 
1,2,3,1,2,3,1... (which you can do easily with a formula 
@if(previous=3,1,previous+1) (where previous is the cell above), lock in 
the values with paste special, and then sort on that column.  There are 
probably other ways as well.

Warning, you are using nominal GDP in place of Y, but Y stands for real 
GDP.  And you are using the CPI instead of the GDP deflator, whereas the 
GDP deflator is the appropriate price level for deflating real GDP.  
(Which is not to say that you should be using  real GDP and the GDP 
deflator at all, if you think about it.)