1. ## solving log equation

Hello, I am trying to understand how this equation works:

formula = Vi * e^-yx
=
5 * e^-1*2.5
=
5 * e^-3.7
=
0.123587

I think there must be an error ? I dont see how they went from the second to third stage.
Thanks for any help.

2. ## Re: solvig log equation

So definitely the initial question states y = 2 and x = 5 = Vi?

3. ## Re: solvig log equation

I have attached an image of the problem details.

y equals the attenuation coefficient (0.01)
x equals the distance which is stated at 2.5km.

I just dont understand how they ended up with 0.12358 as the final answer.

Thanks for helping.

4. ## Re: solvig log equation

Okay I see what the problem is,

In the work they have done they are using beta as y not alpha,

-1*1.48*2.5 = -3.7 (which is what they got)

This probably wont effect you but something you should note is that the exponential should always be unit less, so this means if x = 2.5 m, then the coefficient next to x in the exponential has to be of units m-1, the question doesn't specify the units of each coefficient, alpha or beta, which makes it a little difficult to double check that it should be alpha.

I did a google search and it seems that the units of alpha is m-1 so maybe they just made a mistake and mixed up alpha with beta?