First we need the circumference of the cirkel. As you may know the formula for that is 2×pi×r, with r as the radius of the cirkel. So 2×pi×15=30pi centimeters or 94.24 centimeters. Now we will calculate the fraction of 17 centimeters on 94.24 centimeters. 17/94.24=0.18. That is how fast the wheel will spin. To get it in minutes we now do: 0.18×60=10.82 revolutions per minute.
