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 160 is how many times an intensity corresponding to a magnitude of 125?  Options.
A) 40  B) 100  C) 400  D) 1000  E) 10 000
Increase of 40 in magnitude corresponds to 10^4 increase in intensity:   If intensity for 125 is x then for 135 it'll be 10*x, for 145 it'll be 10*10*x=10^2*x, for 155 it'll be 10*10*10*x=10^3*x and for 160 it'll be 10*10*10*10*x=10^3*x.   Answer: 1000.
<result>D</result>
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 160 is how many times an intensity corresponding to a magnitude of 125?