Scale drawings

- [Instructor] We're told a scale on a blue print drawing of a house shows 10 centimeters represents 2 meters. What number of actual meters are represented by 18 centimeters on the blue print? So pause this video and see if you can figure it out. So the main thing to realize is that a blue print drawing is a scale drawing of something in the real world. In this case of a house. And so what we can do is set-up a little bit of a table here, so let's put the drawing on the left, so this is the blue print drawing. And then this is the real world. Real world on the right. And the unit that we're using, the units that we're using in our drawing are centimeters. So we have centimeters over here. And then the real world, we're thinking in terms of meters. And so let me make a little bit of a table. And so we see that 10 centimeters on the drawing corresponds to 2 meters in the real world. So 10 centimeters in the drawing, corresponds to 2 meters in the real world. Then they ask us what number of actual meters are represented by 18 centimeters on the blue print? So 18 centimeters on the blue print would correspond to what in the real world? Well there's several ways to approach it. One way to think about it is, look to go from 10 to 18, we are going to multiply by 1.8. So to go from what 10 centimeters represents in the real world to what 18 centimeters represents in the real world, you would similarly multiply by 1.8. So times 1.8, which would give us 3.6. 3.6 what? 3.6 meters in the real world. So 3.6 meters in the real world would be what 18 centimeters on the blue print represents. Let's do another example. Jaylynn draws a hen with a scale of 2 units on her graph paper represents 6 meters, 6 centimeters in the real world. The hen is 16 units tall in the drawing. What is the height in centimeters of the actual hen? So once again, pause this video and see if you can figure that out. Alright, so let's just set-up our tables again. So for our table, so we have our drawing, and then we have the real, real world. And in our drawing, it's just these little units on our graph paper, so I'll call it just that, units. And the real world, we're thinking in terms of centimeters, centimeters. And so let me set-up a little bit of a table here, and so we know, and we see that right over here from this scale. We can see two units represent 6 centimeters in the real world. So two units in our drawing represent six centimeters in the real world, and then they say the hen is 16 units tall in the drawing. So it's 16 units tall in the drawing. What would that represent in the real world which would be the actual height of the hen? If two units represent six centimeters, and now we have eight times as many units, well that's gonna represent eight times as many centimeters. So six times eight is 48 centimeters. So what is the height in centimeters of the actual hen? 48 centimeters, 48 and we're done.