Question

A building is 231 feet tall. For a class project, Jim has to make a scale model of the building to place in the front hall display case. The display case is 18 inches tall. Which scale will allow him to make the tallest model that will fit in the display case?

Answer 1

A 1 inch = 15 feet
B 1 inch = 10 feet
C 1 inch = 20 feet

Answer 2

Proportions... made more complicated by the introduction of units of measure :)
First, convert feet to inches. What's 231 feet?

Answer 3

HUH

Answer 4

231 feet... how many inches is that?

Answer 5

2772 in

Answer 6

Okay... so to get the scale model, or proportions right, we have to make it so that
2772 = 18 times some unknown number
or
2772 = 18k
Find k.

Answer 7

how do I do tht

Answer 8

Or, if you want to be formal...
2772:18 = k:1

Answer 9

what untis r for it

Answer 10

Oh.... right
We started with
231 ft : 18 in = k : 1 in
But we can't have that, so we have to have 231 ft in inches... so
2772 in : 18 in = k : 1 in

Answer 11

idk how to do tht

Answer 12

Well, in that case, you just divide 2772 by 18. What do you get?

Answer 13

154

Answer 14

That's right. So 154 = k/1
or 1k = 154
But that's in inches. How many feet is 154 inches?

Answer 15

12.83

Answer 16

Right. 1 inch corresponding to 12.83 feet is the largest you can do. That means anything larger than 12.83 feet per inch, and the scale model won't fit. Do you know the answer now? :)

Answer 17

yeah I got it now thanks