Question

A picture is 46 cm by 32 cm. A scale diagram of the picture must fit in a space that is 3 m by 2 m. Which scale would be the most reasonable one to use for the scale diagram?

Answer 1

A picture that is 46cm by 32 cm must fit in a space that is 3m by 2m

First, let's rewrite both of these dimensions in the same units.

Knowing that:

1m = 100cm

Then the dimensions of the space can be rewritten from:

3m by 2m

to:

300cm by 200cm

So, if we enlarge our original picture by a scale factor K, the new dimensions of the picture will be:

K*46cm by K*32cm

Now we just need to find a value of K such that:

K*46cm is something near to 300cm

K*32cm is something near to 200cm

First, we can solve the equation:

K*46cm = 300cm

solving this for K we get:

K = 300cm/46cm = 6.5

While if we solve the equation:

K*32cm = 200cm

we get:

K = 200cm/32cm = 6.25

So we got two possible scale factors.

Which one we should take?

Notice that if we wanted to use the larger one (K = 6.5) for the 32cm side. the new length would be:

32cm*6.5 = 208cm

This is larger than the 200cm of space that we have

Then we can not select the larger option, we can only take the other value:

K = 6.25

Then we can conclude that a reasonable scale factor to use is K = 6.25