Need help!

[prepgmat]

Please, need some help with this one:

On a certain scale of intensity, each increment of 10 in magnitude represents a tenfold increase in intensity. On this scale, an intensity corresponding to a magnitude of 165 is how many times an intensity corresponding to a magnitude of 125?

a) 40
b) 100
c) 400
d) 1,000
e) 10,000

[Nidhs]

say, we have a scale with magnitude n and intensity y. the question says that for each increment of magnitude 10....intensity increases 10 times.
Therefore n+10 corresponds to 10y, n+20 corresponds to 10^2y and so on.

Now lets keep n as 125 and intensity y
if n is 165...intensity will be 10^4y

My answer would be (E).

[prepgmat]

Thanks Nidhs. And yes, the answer is E. Nice approach to the problem.