The volume of a swimming pool from its construction plan is calculated to be 20 cm3. Find the volume of the pool if the plan has a scale of 1 : 75

1:75;

what this actually means is that any dimension on the plan is 1/75 of actual dimension of the pool or any dimension of the actual pool is 75 * the dimension on the plan. But this is, in fact, a linear scale so we will have to do something when using it:

The 20cm3 volume on the plan is attained from length*width*height.

Each dimension will need to be multiplied by 75 to find the volume of the actual pool:

Vol of pool: 75^3*20 = 8437500cm^3

I believe this should be the answer