A bicycle wheel has a diameter of 0.81m. How many complete revolutions does it make in 1km?  Select.
A) 246
B) 448
C) 393
D) 710
E) 223
1 revolution = 3.14 * diameter.   Number of revolutions in 1km = 1000m / ( 3.14 * 0.81m ) = 393.2. Hence 393 complete revolutions.   Answer 393
<result>C</result>
A bicycle wheel has a diameter of 0.81m. How many complete revolutions does it make in 1km?