Distance traveled = 70 m
Number of rotations = 35
We know, Circumference * Number of rotations = Distance traveled
So, C = 70 / 35
C = 2 m
Now, we know, diameter = C / π
So, d = 2/3.14 = 0.64 m
In short, Your Answer would be: 2/π m or 0.64 m
Hope this helps!