find the general term that describes the following sequens

Question

600,300,150,75

I the thing is that you divide each of them by 2

so I would go
y(n)= 600/ 2^n

but how do I check if this is right?
is this right?

It is right.

That would certainly be a good guess, and 'a' possible sequence. It would be the most natural one to use too in my opinion.
How to test it?
You're hypothesizing that the general or n^th term is 600/2ⁿ so for n=1 you'd have
600/2 = 300, so you might want to alter the general term to be
600/2^n-1 then for n=1 you'd have
600/2^1-1 = 600/2⁰ =600/1 = 600
For n=2 you'd have 600/2¹ = 300
Then y(n) would be right for the first 4 terms of the sequence.