Magoosh PT Exponent/Root problem

Got the question right (answer was 6.5, I put 13/2), but test marked it as wrong. The instructions were to enter the answer in the blank (the question didn’t specify whether to put the answer as a decimal or fraction) and so I entered 13/2. The answers are the same, and I wanted to know if this would be marked wrong on the actual GRE? Much appreciated.

There are two cases. If the output is a simple text box, it’s a decimal. It’s only a fraction if the output is a fraction itself.

I don’t think ETS would allow you to enter a fraction for a simple text box in the actual test.

Thank you so much!