1. 7.5.3 Writing Proportions

2. Tables, Rows, and Columns
Use a table to help you in writing proportions
You can use the columns…
2 boxes = 3 boxes (numerators have the same units)
$ x dollars (denominators have the same units)
You can use the rows…
2 boxes = $ (the units are the same on
3 boxes x dollars each side of the proportion)
Last Weekend
This Weekend
Popcorn Boxes 2 3
Total Cost
$9.00
x dollars

3. Batting Average batting average = at bats (A)
hits (H) .
batting average = at bats (A)
A player whose batting average is .250 is has a
250 batting average.
20 hits = batting average = hits .
80 at bats at bats

4. How many hits?
Determine the hits needed for each batting average below. 50 times at bat; batting average is times at bat; batting average is times at bat; batting average is time at bat; batting average is 1.000

5. Mental Math
Step 1: Think about the relationship between the two numbers on each side of the equal sign.
Example:
3 . = x .
· ? = 8 2 · 4 = 8
Step 2: Apply that relationship to the other number to solve for x.
3 . = x .
· 4 = 12 x = 12

6. Solving Proportions Using Mental Math
5/8 = 20/d 7/z = 14/10 21/24 = x/8

7. Homework
Pg. 182
#1, 4*, 5*, 6*, 7*, 8*, 10*, 12, 17, 19, 20, 21
*note: you don’t need to solve these; just write the proportion (the two fractions with the equal sign in between them).