The model of the house was made in a scale of 4:20. find the height of the house if the height of the layout is 1.5m.

Decision:

Let’s express the height of the layout in cm:

1.5 m = 150 cm.

Find the height of the house using the proportion:

4: 150 = 20: x;

To find the unknown extreme term of the proportion, it is necessary to multiply the average terms of the proportion, and then divide their product by the known extreme term of the proportion.

x = 150 × 20: 4;

x = 750 (cm) – the height of the house.

Let’s express the height of the house in meters:

750 cm = 7.5 m.

Answer: the height of the house is 7.5 m.