A bicycle wheel has a diameter of 0.81m. How many complete revolutions does it make in 1km?
Choose the correct choice from the following answers.
A) 246
B) 448
C) 393
D) 710
E) 223

Rationale: "1 revolution = 3.14 * diameter . number of revolutions in 1 km = 1000 m / ( 3.14 * 0.81 m ) = 393.2 . hence 393 complete revolutions . answer c"
Answer: C