What is the cost of building a 1m wide path that is 10cm thick around a pool 7mx4m if the concrete used costs $129 per m^3.

Length of pool = 7m

Breadth
of pool = 4m

Since we need a path of width 1m around the
pool, the  outer borders of the path should extend 1m more on all sides of the
pool

so we have path which looks like being made of 4
rectangles

-- the upper and lower ones which are of length
9m and width 1m

--the side ones with length 4m and width
1.

So the total area will
be

2* (9*1) +2*(4*1) = 18+ 8
=26m2

T find the perimeter, consider the out ward edges of
the path.

The length of the outward edges will be 9m, 4m
,9m and 4m respectively

So the perimeter =9*2+4*2 = 26
m

To find the cost of concrete of depth 10 cm = 0.1 m, we
have to find the volume

The longer sides of the path will
have volume = 9(length)*1(width)*0.1(depth) = 0.9m3

The
shorter sides will have volume = 4*1*0.1 = 0.4m3

so the
total volume =0.9*2 +0.4*2 = 1.8 +0.8 = 2.6m3

Cost is $129
per m3

So the total cost is 129 *2.6 =
$258