I tried to solve it Gregs way and i got the answer as 210%, seems like that isn’t the answer. Let me know if this is the right way
X (defined for 2005) = 1.05Y(defined for 2001)
Z(defined for 2009) = 2X(defined for 2005)
I translated price of the metal on 2009 is what percent of 2001 as
Z = (p/100)*Y
Subbing Z=2x and X=1.05Y
I got 2x= (p/100)*(x/1.05)
the answer for what percentage is 210 right?
I believe 2 times is only 100% increase, can you try again with 200% increase as per the question?
Wouldn’t 200% be denoted as Z = 200/100 (X)?
yes but one needs to add the increase in percent to the number itself. For ex. 200% of 100 is 200, but the final price (since the precious metal’s price is 200% greater) would mean 200 + 100 = 300 = 3 times.
Ohhh alright, i just got the answer. I know its too much to ask, can you send how you would solve the question. Like how the equation for Z=3x is intuitively setup, because in my mind applying 1+ isn’t intuitive idk why. So you are saying there should always be a (1+2) x?
Similarly this for example. I used gregs formula for percentage increase which is (Small - Big) /Small
The numerator can be anything as long as the denominator is “Small”
So I applied the Small as Y and the big as 1.40 Y (since 40% increase). So (Y-1.40Y) / Y…this doesn’t equate to 140 percent. Is this similar to the problem above, should I be adding another 1 to the 1.40 above?
price in 2001 = x
price in 2005 = 5% more than 2001 = 1x + 0.05x = 1.05x
price in 2009 = 200% more than 2005 = 1.05x + (1.05x+1.05x) = 3.15x
which is 315 percent of x
I believe understanding the wording of the question is key.
So there can be a difference such as saying “at 200% of x” rather than " 200% greater than x". The first phrase value would be 2x whereas second case would be 3x.
Hope this helps!
Jeet
I believe this is a simple question which can get tricky if you overthink it (which is what GRE wants us to do).
If you check what the question is asking, its essentially the % of new Y when compared to old Y. In other words what percentage when multiplied to old Y will give me new Y.
It is not asking the percentage increase (which is the formula you’re trying to use). It’s just asking a basic question like 20 is what percent of 10. So your formula should be (20/10)*100 = 200%.
I’ve shown two ways of doing above question, hope this helps. 
Oops i guess I fell for the trap. Thanks a bunch, this helps.
