An interval of 3 hours 40 minutes is wrongly estimated as 3 hours 45.5 minutes. The error percentage is :

Answer: Option A

Correct time :
= 3 hrs 40 min
= (3 × 60 + 40) min
= 220 min
Error = 5.5 min
Error % :
= $$\left(\frac{5.5}{220}\times 100\right)$$  %
= $$\frac{5}{2}$$ %
= 2.5%