math help?

Question

the radius to the outside edge of a circular path is 12 feet greater than the radius to the inside edge. of the folliwing, which is the closest approzimation to the positive difference, in feet, between the circumferences of the two edges of the path.

a 12
b 15
c 25
d 37
e 75

Answer 1

Answer is e 75
lets say radius of inner circle is x, then the radius of outer circle is x+12.
Circumference of inner circle is 2*3.14*x = 6.28x
Circumference of outer circle is 2*3.14*(x+12)= 6.28x+75.36

Difference between the two is 75.36, hence the answer is e 75.

Answer 2

C =2 pi r
= 2 x 3.14 x 12
=75

so e 75 is the answer.

Answer 3

let radius to the inside edge be x
therefore radius to the outside edge of a circular path which is 12 feet greater = 12+x

c=2*pi*r
therefore difference between circumferences =
[2*3.14*(12+x)]-[2*3.14*x]
= [6.28*(12+x)]-[6.28x]
= [75.36+6.28x)]-[6.28x]
= 75.36+6.28x-6.28x
= 75.36+0
therefore=75.36
therefore answer=e (75) which is the closest to 75.36 .

Answer 4

Let R = outer radius
r = inner radius
∆c = 2πR - 2πr
∆c = 2π(R - r)
∆c = 2π(12)
∆c ≈ 75 ft.

Take care
bye

Answer 5

e 75 it will differ by 2*3.14*12

Answer 6

Let R = outer radius
r = inner radius
∆c = 2πR - 2πr
∆c = 2π(R - r)
∆c = 2π(12)
∆c ≈ 75 ft.

Answer 7

Most of them above me have answered it right...

answer is (e) 75 feet...

Answer 8

e 2*3.14*12=75.36

Answer 9

i'd say this is a trick question and so i'd go with 12 A.

Answer 10

Sorry my head's spinning thinking about it so no answer I'm afraid..