If 10^x equals 0.1 percent of 10^y, where x and y are integers, which of the following must be true?

A. y=x+2
B. y=x+3
C. x=y+3
D. y=1,000x
E. x=1,000y

Question

If 10^x equals 0.1 percent of 10^y, where x and y are integers, which of the following must be true?

A. y=x+2
B. y=x+3
C. x=y+3
D. y=1,000x
E. x=1,000y

kropot72 · Answer

The given relationship between x and y can be expressed as
$$\large 10^{x}=\frac{10^{y}}{1000}\ .........(1)$$
Does that make sense as a first step towards a solution?

anonymous · Answer

hmmmm.... why?

anonymous · Answer

wait nvm i get it

anonymous · Answer

please go on

anonymous · Answer

wait why is the 1 at the end? what is that?

kropot72 · Answer

To find 0.1% of a quantity, we divide the quantity by 1000. 
The (1) at the end is simply a reference number for this equation. We need to use equation (1) to form another equation.

anonymous · Answer

okay

kropot72 · Answer

Next step is to take logs of both sides of equation (1). Please do that and post your result.

anonymous · Answer

Hey we don't use logs for this question

kropot72 · Answer

Who says we don't use logs?

anonymous · Answer

The GRE book I'm using ... There isn't any logs at all

kropot72 · Answer

Does the book suggest a method of solving that doesn't use logs?

anonymous · Answer

well the solutio|dw:1436987482723:dw|n is this but i don't understand it....