Answer:
(b) He used the radius instead the diameter.
Formulae to calculate the circumference of the tire is = π × d.
where π is 22/7 and d is 15.
Explanation:
when we calculate the circumference the answer will be
π × d =22/7 x 15 = 47.1
while the answer Mario computes is 23.55 inches.
Thus the error occurs in the formulae that are, Mario multiplies with the radius instead of diameter.
π × d/2 = 22/7 x 15/2 = 23.55