Agear on a bicycle has the shape of a circle one gear has a diameter of 4 inches and a smaller one has a diameter of 2 inches justin says that the circumference of the larger gear is 2 inches more in the circumference of the smaller gear do you agree explain your answer

Justin is not correct.  It is true that the diameter of the larger circle is 2 inches more than the smaller circle diameter.

Use formula pi D or 3.14xDiameter

Large gear:

3.14(4)

=12.56 in

smaller gear

3.14(2)

=6.28

actually, the larger gear in circumference is 6.28 more than the smaller gear.  Also, 12.56/2=6.28 ...so, the larger gear circumference is 2 times the diameter of the smaller gear.

12.56-6.28=6.28