RATIO AND PROPORTION
Proportion as Ratio
Activity 3: Finding Distance
To set up and solve proportions.
Introduction:When you were finding ratios, you were also using proportions. A proportion is statement indicating that one ratio is equal to another. We say that any pair of entries in the tables we have in previous activities is proportional to any other pair of entries.
The proportions that relate one revolution to 2, 3, and 4 revolutions are 1/239 = 2/478, 1/239 = 3/717, and 1/239 = 4/956, respectively.
The proportion which relates the gear ratios is 22/44 = 25/50,
or alternately, 44/22 = 50/25.
Part C (individual activity)
X = 288 X = 121 X = 850.5
X = 16 X = 20 X = 544.5
Closing Discussion Are the following proportions the same? Why or why not? The two proportions are not the same. In the first case X=100 and in the second case X=4.
10/50 = 20/x 10/50 = x/20
How can you make sure that you always have "X" in the correct position
when setting up a proportion? Make sure that the numerators correspond
to the same type of value; likewise, for the denominators.
Area 10 Mathematics and Technology Professional Development Center
Permission is granted to duplicate these materials for classroom use.
Last updated on 1/30/1999