SOLUTION: When mineral deposits formed a coating 1mm thick on the inside of a pipe the area through wich fluid can flow was reduced by 20%. Find the original inside diameter of the pipe.
(R
Question 409077: When mineral deposits formed a coating 1mm thick on the inside of a pipe the area through wich fluid can flow was reduced by 20%. Find the original inside diameter of the pipe.
(Remeber: area of circle = pi(r^2) and diameter = 2r)
Thanks for the help =) Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website! I think they are saying that the area of the pipe opening has been
reduced by 20%.
Let = original area
Let = original radius
----------------------
If the diameter is reduced by 1 mm, then the
radius is reduced by .5 mm.
given:
(1)
(2)
------------------------
(2)
substituting from (1):
(2)
(2)
(2)
(2)
(2)
Use quadratic formula mm
The original diameter = 2r, or 9.472 mm
check answer:
(2)
(2)
(2)
(2)
(2)
(2) mm2
and
(1)
(1)
(1) mm2
OK
Hope I got it
