Answer:
325.76 revolutions
Explanation:
The tire radius is diameter/2: 42/2 = 21
And now we can discover the lenght of the tire circumference. The lenght of a circumference is given by 2×radius×π, and let's consider π=3.14, and let's use the radius in meter (21 cm = 0.21 m):
2•0.21•3.14 = 1.32 m of lenght
Now, you divide the distance the car moved by the lenght of the tire circumference and you will find how many revolutions the tire makes:
420/1.32 = 325.76
