Question

a scale drawing has a scale of 0.25 in : 12ft Find the length on the drawing for an actual length of 15 ft.

Answer 1

0.3125 inches

You can get this by dividing the scale factor by the length and then multiplying by the new length.

Answer 2

Let the length on drawing for actual length of 15 ft = x inches

And they say that the ratio of drawing length to actual length is 0.25 in : 12 ft

it means we can make a ratio proportion such that

`(0.25_(in) )/(12_(ft)) = \frac{x {in}}{15_(ft)}`

Cross multiplying we get

0.25 * 15 = 12*x

3.75 = 12 x

Divide both sides by 12

x = 0.3125

It means

the length on drawing for actual length of 15 ft = 0.3125 inches