Powerprep 2 answer help

[shuayjye]

Hello,
So I did a quick run of powerprep 2 preview and I am stuck on the last question.
At store T, the dollar amount of sales for 2007 was what percent of the dollar amount of sales for 2008? (nearest .1%)
Store T percent change:
2006-2007 +17%
2007-2008 -8%
I can see the answer of 108% since 2008 becomes the starting point and the change is +8% but the answer the test gave was 108.7%

There must be something wrong in my train of thought and calculation but for the life of me I cannot figure out how to work though this.
Thank you for any help.

[abhishek1787]

Can you post the complete question please?

[shuayjye]

I did post the complete question.
At store T, the dollar amount of sales for 2007 was what percent of the dollar amount of sales for 2008?
I will take a screen shot and attach it
I hope this helps.

[abhishek1787]

shuayjye,


Consider in 2006 dollar amount sale was 100.
2007-->17% increase so it becomes 117.
2008-->8% decrease so 117 becomes 107.64(92% of 117)


Finally they are asking for 117 is what % of 107.64


100*117/107.64 = 108.695=108.7

[shuayjye]

abhishek1787,
Thank you for the explanation, and I understand how they got the answer now. The problem is the questions ask about 2008 to 2007. Why do we start at 2006? If the question mentioned in "in perspective of 2006" it would make sense.
Since I am looking from 2008 sales I made that 100% then 2007 had a +8% compared to 2008 to make 108%. Maybe this is just wrong thinking but I would like to know if this is an assumption that we would start from 2006. What happens if they had data from 2005 would we start at 2005 then?

[abhishek1787]

From the graph it is given that percentage change from 2006 to 2007 is +17%,so i took the starting point as 2006.What ever may be the starting year you can take initial number for percentage prob as 100(good practice) and then add the increase/decrease percentage to it.

For problems of this sort first try to calculate all the values required from the graph given and then go for the question and apply the values.

Hope this makes sense.

[shuayjye]

It does make sense, I wanted to make sure this was a common way of solving this type of problem. It might not be logical to me but getting a good score on the GRE is all that I care about. I am sure as I go along I will have more questions. Thank you again for your help and patience.

[mxplusb]

There is no reason to know the % change from 2006 to 2007. That's just there to throw you off.

Adjusting abhishek1787's approach,

Consider in 2007 dollar amount sale was 100.
2008-->8% decrease so 100 becomes 92

But you don't want the percentage of 2008 sales relative to 2007, you want the 2007 sales relative to 2008. So you take 100/92


=108.7

[shuayjye]

mxplusb,
I love you answer, it makes complete sense to me and I am ashamed that it never occurred to me.

[mxplusb]

Thank you. I am glad I could help.