Question

In the diagram, a building casts a 21-ft shadow and a flagpole casts a 6-ft shadow. If the flagpole is 15 ft tall, how high is the building? Round to the nearest tenth.

Answer 1

Ratio Problem

15 tall Flagpole 6 shadow Flagpole
-------------------- = -------------------------
x tall build 21 shadow build

6x = 315
x = 52.5

Answer 2

52.5 ft high is the building

Explanation:

Proportion states that two ratios or fractions are equal

As per the statement:

In the diagram,

a building casts a 21-ft shadow and a flagpole casts a 6-ft shadow.

If the flagpole is 15 ft tall.

Let x ft be the height of the building.

then by definition we have;

`\frac{\text{Height of the building}}{\text{Shadow of the building}}=\frac{\text{Height of the flagpole}}{\text{Shadow of the flagpole}}`

`(x)/(21) = (15)/(6)`

By cross multiply we have;

`6x = 315`

Divide both sides by 6 we have;

`x = 52.5` ft

Therefore, 52.5 ft high is the building