Beat The GMAT a GMAT & MBA community

My question deals with how to attack two problems.

1. 12th Ed. 156

Is 5^k < 1,000?

l) 5^k+1 >3,000
ll)5^k-1 = 5^k-500

I rephrased this question to be "Is k< or = 4?"
Answered B correctly.

I just completed the MGMAT rephrasing online lab and the last question is a warning against over simplifying your rephrasing. The example used is as follows.

Is 2^x > 100?

l) 2^(sq root)x = 8
ll) 1/2^x < .001

They make a point to say that a RP = "Is x > or =7?" IS NOT A CORRECT RP. They explain that the question does not explicitly state that X is an integer and therefore there is no real RP possible.

That said, you should still get the correct answer D with the RP "Is x > or =7?" because if x were 6 the 2nd statement would not be true, and if x = 7 or greater it is true. Or the denominator must be greater.
I guess you could say that 1/2^6.? could be true but what is the likely that the GMAT would hold us to that???

So, what is the correct protocol here??