Helga M. answered • 10/01/12

Lots of Experienc: 20 years College Teaching, 35 years Tutoring

All proportion problems involve two descriptions in two different ways.

This problem asks for height, and one decription is

height of person and height of ceiling

another is height before shrinking and height after shrinking.

Once you have determined this, you write a table like this

first descripton first descripton

way 1 way 2

second description

way 1

second description

way 2

For your example, that is

height of person height of ceiling

height before 68 96

height after 12 c

shriking

From this table you can read off the proportion by placing fraction bars in the same place and an equal sign in between the two fractions. Whether you go across or down doesn't matter. That is you can get either

68/12 = 96/c by creating the

fractions vertically

or

68/96 = 12/c by creating the

fractions horizontally

In fact you can even go from right to left or bottom to top. The important thing is just that you do it the same way in both cases. That is you could also get

12/68 = c/96

and

96/68 = c/12

Try it out. Solve all four equations for c. You will get the same answer each time. So the most important thing is to set up your table correctly.