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Explanation:
We have two concentric circles. Think of a bulls-eye on a dart board. The inner circle is the garden itself. The outer circle is the garden plus the surrounding pathway. What we're interested in is the area of the outer ring, which is the area of the garden path only.
To find this ring area, we'll need to find the area of each circle.
A = area of the smaller circle
A = pi*r^2
A = pi*12^2
A = 144pi
Notice how I took half of the 24 yard diameter to get the radius of 12 yards.
B = area of the larger circle
B = pi*r^2
B = pi*15^2
B = 225pi
Subtract the two results
C = area of the outer ring, aka the garden path only
C = B - A
C = 225pi - 144pi
C = (225-144)pi
C = 81pi
We're told to use 3.14 in place of pi
C = 81*pi
C = 81*3.14
C = 254.34
The garden path has an area of roughly 254.34 square yards.
1 bag of sand covers 8 square yards.
So we'll need (254.34)/(8) = 31.7925 = 32 bags of sand
