This is one of the basic and conceptual question from similarity of triangles chapter in which

(i) If the height of the model is 80 cm, we have to find the actual height of the building in metres.

(ii) If the actual volume of a tank at the top of the building is 27m3 , we need to find the volume of the tank on the top of the model

and

The model of a building is constructed with the scale factor 1:30.

Book-ML Aggarwal avichal publication

Class 10, Similarity, chapter 13.3, question no 19