How far will an aircraft travel in 2-1/2 minutes with a groundspeed of 98 knots?

I understand the answer is 4.08NM

But I want to know how one would calculate the answer?

Two answers.

On the ground, real calculation -> 98 knots equal 98 nautical miles per 1 hour equal 60 minutes, so the 2.5/60 fraction of 98 nautical miles = (2.5/60)*98 = 4.083 nauticals

In the air, head calculation -> 98 knots is almost 90 knots +10% and 90 knots is 1.5 nauticals per minute, 1.5 times 2.5 is 3.75 plus 10% roughly equals 4.1 nauticals - good enough