What is the magnitude of the aftershock

[gatita0225]

Homework Statement

An earthquake with a magnitude of 5.4 is 39 times as intense as an aftershock that occurs 5 hours later. What is the magnitude of the aftershock.

Homework Equations

m=log_10(i/i_0)

The Attempt at a Solution

I know that I what to find the magnitude
m=log_10(39/i_0)
I am stuck because I do not know what # do I replace "/i_0' with..please help!?

 

[RUber]

You don't need it, the i_0 is irrelevant.
Look at it this way: m1 = 5.4 = log(39x/i_0) = log(39x) - log(i_0).
and m = log(x/i_0) = log(x) - log(i_0).
You can cancel out the i_0, since it won't help you.

*edit* Even more simply, let x= i/i_0, then there is even less to worry about. Just remember the product rule for logarithms.