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Calculations and the numbers in the post by @MathLover1 are incorrect.
I came to bring a correct solution.
height = 1.5m
length = 5m
breadth = 3m
1.1. what is the surface area of the inside of the pool?
the surface area of the inside of the pool is the area of the bottom plus the area of the sides
the area of the bottom is length*breadth = 5m*3m = 15 m^2 <<<---=== my correction is here
the area of the two parallel sides is 2*length*height = 2*5m*1.5m = 15m^2
the area of the two other parallel sides is 2*breadth*height = 2*3m*1.5m=9 m^2
the surface area of the inside of the pool is
Surface Area = 15m^2 + 15m^2 + 9m^2 = 39m^2. ANSWER <<<---=== my correction is here
1.2. The pool will be covered in two layers of cement. Calculate how much it would cost to line the pool
if the cement cost R150.00 per square meter. // I assume that R150.00 is the cost of one layer per square meter.
R 150.00*2*39 = R 11700. ANSWER <<<---=== my correction is here
1.3. Calculate the percentage of the pool that could be filled by the water in the tank. (Remember 1m^3 =1000litres).
This percentage is between 0% to 100%, and can not be calculated precisely,
since the volume of the water in the tank is not given in the post.
Solved (in a right way).