Question

A building casts a shadow 39 m long. at the same time, the shadow cast by a 59-cm tall pole is 71 cm long. find the height of the building.

Answer 1

Solving this problem is just pretty straight forward. All we have to do is to use the concept of ratio and proportion.

First, let us say that the height of the building takes the value of variable x.

From the given, we know that the ratio of the building to its shadow is

x : 39 m

And the ratio of the pole to its shadow is

59 cm: 71 cm

To solve for the value of x, we equate the two:

x : 39 = 59 : 71

We know that the symbol of ratio which is “:” also means division, therefore:

x /39 = 59 / 71

x = 59 * 39 / 71

x = 32.41 m

 

Therefore the building is about 32.4 m high