Please help asap thank you

Ineed with number 17 i don’t get it at alll

Identify the number as a regional or irrational.explain. 291.87

The maximum distance (in nautical miles) that a radio transmitter signal can be sent is represented by the expression 1.23h√, where h is the height (in feet) above the transmitter. estimate the maximum distance x (in nautical miles) between the plane that is receiving the signal and the transmitter. round your answer to the nearest tenth.