SOLUTION: the inner circumference of track is 220 meter. the track is 7 meter wide everywhere. calculate the cost of putting up fence along the outer circle at the rate of rupees 2 per meter

Algebra ->  Surface-area -> SOLUTION: the inner circumference of track is 220 meter. the track is 7 meter wide everywhere. calculate the cost of putting up fence along the outer circle at the rate of rupees 2 per meter      Log On


   



Question 820323: the inner circumference of track is 220 meter. the track is 7 meter wide everywhere. calculate the cost of putting up fence along the outer circle at the rate of rupees 2 per meter.
Answer by LinnW(1048) About Me  (Show Source):
You can put this solution on YOUR website!
Steps to solve.
1) Find the radius r of the inner circle.
2) Find the radius R of the outer circle.
3) Find a formula for the outer circumference O .
4) Multiply O to give us the amount in rupees.
1) Use the formula for circumference C = (pi)(2r)
C = (pi)(2r)
divide each side by (pi)
C/(pi) = 2r
divide each side by 2
C/(2(pi)) = r
2) R, the outer radius = r + 7 = C/(2(pi)) + 7
3) O, the outer circumference = (pi)*(2R) = %28pi%29%2A%282%2A%28+C%2F%282%28pi%29%29+%2B+7+%29%29
or %28pi%29%2A%282%2A%28+220%2F%282%28pi%29%29+%2B+7+%29%29, where 220 is the inner circumference.
4) Multiply by 2 to give us the number of rupees
2%2A%28%28pi%29%2A%282%2A%28+220%2F%282%28pi%29%29+%2B+7+%29%29%29=
4%2A%28pi%29%2A%28+220%2F%282%28pi%29%29+%2B+7+%29=
%28+%284%2A%28pi%29%29%2A%28220%2F%282%28pi%29%29%29+%2B+7%2A%284%2A%28pi%29+++%29+%29=
%28+%282%29%2A%28220%29+%2B+7%2A%284%2A%28pi%29+++%29+%29=
+440+%2B+28%2A%28pi%29+, the number of rupees