there is a pool of radius x and there is a pathway around the pool with a width of 4 feet. find the radius of the pool if the path area/ pool area = 11/25. 1) 12 2) 20 3) 25 4) 29
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the radius of the pool be x.
Then area of the wall and pool = π(x + 4)²
Area of the pool = πx²
Area of the wall = area of wall and pool - area of pool
GIVEN:-
area of wall/area of pool = 11/25
so, area of wall = 11/25 * area of pool
therefore, 11/25πx² = π(x + 4)² - πx²
π(x² + 16 + 8x - x²) = 11/25πx²
(16 + 8x) = 11/25x²
25(16 + 8x) = 11x²
400 + 200x = 11x²
11x² - 200x - 400 = 0
11x² - 220x + 20x - 400 = 0
11x(x - 20) + 20(x - 20) = 0
(11x + 20)(x - 20) = 0
Hence, x = 20 , x = -11/20[x can't be negative]
Hence, option ( 2 ) is correct
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Answer:
20is correct
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