As you can see, the shape of the reservoir is disproportioned and cannot be calculated using normal methods.1.Estimate the amount of water in the MacRitchie Reservoir during the dry season if the depth is 2.5m.
There are two solutions to this question but the first method would be the most appropriate solution of the two.
Method 1: By using method 1, we would get a more accurate solution. For this question,a cuboid is used. 
Given the dimension of Macritchie Reservoir, all we have to do is multiple the length, breadth and height/width/diameter.
In this case, the approximate length,breadth and diameter is :
Length ____(2cm) 120000cm,
Breadth____(1.4cm) 84000cm
Diameter____250cm
(Measurements are according to measurements on map)
(1 cm is approximately 60,000 cm)
As the shape of the reservoir is taken after the shape of a rectangle while the area of the cuboid is taken after a square, some parts of the rectangle should fit into the square, making it an approximate area. Thus, if you find the product of the length, breadth and width,you would be able to get an approximate amount of water during a dry season.
(The 'cut and paste' method)
Method 2: Method 2 is the use of a cylinder.The solution to finding the volume of Macritchie Reservoir is TT x R x R x H . In this case, the radius is 125 cm , the height is 75,0000cm, and TT is 3.14cm.
Although it is one of the method, the answers of both methods are totally different. If you use a cylinder to calculate the volume of the water, the circular portion of the cylinder would be on the water and instead of a flat surface of water, there would be a semi-circle floating on the water.
If you were to use this method, the solution would be
(TT) 3.14cm x (R) 125cm x (R)125cm x (H) 750000cm = 7359375 thousand ml. (estimated value is 7.4 million)
If both of them were to be compared, method one would be a more understandable solution to solve this type of questions.
