Question

the plan of a shopping complex is drawn to a scale of 1:400. A supermarket on the plan occupies an area of 0.25m square, calculate its actual area in hectares

Answer 1

The scale of 1:400 states a linear relation and we know that the areas of similar figures is proprotional to the square of the corresponding sides
so ...
actual area/.25 = 400^2/1^2
actual area = 40000 m^2
since 1 hectare = 10,000 m^2
the actual area = 40000/10000 = 4 hectares

or

.25 m^2 would give a side of .5 m on the scale drawing
which would be .5(400) or 200 m in real life
so the area of the complex in real life is
200 m by 200 m = 40,000 m^2 , etc same as above