PROPORTIONS

 Proportion problems are word problems where the items in the question are proportional to each other. In this lesson, we will learn the two main types of proportional problems:  Directly Proportional Problems Directly Proportional Problems  Inversely Proportional Problems. Inversely Proportional Problems

Directly Proportional  The question usually will not tell you that the items are directly proportional.directly proportional  Instead, it will give you the value of two items which are related and then asks you to figure out what will be the value of one of the item if the value of the other item changes.

Inversely  Inversely Proportional questions are similar to directly proportional problems, but the difference is that when x increase y will decrease and vice versa  The most common example of inverse proportion problems would be “the moremen on a job the less time taken for the job to complete”for the job

 Proportion problems are usually of the form: If x then y. If x is changed to a then what will be the value of y?  For example, If two pencils cost $1.50, how many pencils can you buy with $9.00?

 _id= _id=54705  _id= _id=2934

Example 1  Jane ran 100 meters in 15 seconds. How long did she take to run 1 meter? Step 1: Think of the word problem as:  If 100 then 15. If 1 then how many? Step 2: Write the proportional relationship:

Example 2 If of a tank can be filled in 2 minutes, how many minutes will it take to fill the whole tank?  Step 1: Think of the word problem as: If then 2. If 1 then how many? (Whole tank is )  Step 2: Write the proportional relationship:

 A car travels 125 miles in 3 hours. How far would it travel in 5 hours?  Step 1: Think of the word problem as: If 3 then 125. If 5 then how many?  Step 2: Write the proportional relationship:

 It takes 4 men 6 hours to repair a road. How long will it take 7 men to do the job if they work at the same rate?  Step 1: Think of the word problem as: If 4 then 6. If 7 then how many?