Download Ratio, Proportion, and Percent

Name ———————————————————————
SECTION
3
Date ————————————
Ratio, Proportion, and Percent
Lesson 3: Writing Proportions
a
b
c
d
It is written as a fraction equal to a fraction, } 5 }. Two fractions
are equal if, when written in simplest form, they have the same
numerator and denominator.
A proportion is an equation stating that two ratios are equal.
EXAMPLE 1
1
Write two different proportions using the ratio }2 .
Write equivalent fractions:
Write proportions:
}5}5}
1
2
132
232
2
4
}5}
1
2
133
233
3
6
}5}
}5}5}
EXAMPLE 2
1
2
2
4
1
2
3
6
HINT
Multiplying or dividing
the numerator and
denominator by the same
number creates an equal
fraction.
Can you write a proportion using the ratios
6
8
2
3
} and }?
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
6
332
3
2
5}
5 }4 and }3
8
432
2
3
No; }4 Þ }3, so you cannot write a proportion.
}
Practice: First Try
Write two different proportions using the given ratio.
1
1. }
3
2
2. }
5
3
3. }
4
4
4. }
7
1
5. }
12
5
6. }
8
3
7. }
3
5
8. }
2
3. RATIO, PROPORTION
3. Writing Proportions
Write fractions in simplest form, then compare:
Tell whether you can write a proportion using the two ratios.
8 3
9 3
1 2
8
4 }
9. }, }
10. }, }
11. }, }
12. }
9 , 27
5 10
12 2
15 5
1 }
4
13. }
3 , 12
9 16
14. }, }
8 18
8 }
2
15. }
4, 1
10 }
3
16. }
15 , 4
McDougal Littell Middle School Math
Remediation Book Lesson 3.3
69
Name ———————————————————————
Date ————————————
Practice: Second Try
1
1. }
4
2.
}
5
3
2
3. }
3
4.
}
4
5. }
10
6.
}
5
6
9
7. }
4
8.
}
3
9. }
1
10.
}
7
7
5
11. }
8
12.
}
3
13. }
4
14.
}
4
3
1
15. }
5
16.
}
20.
}, }
1
6
4
5
7
6
Tell whether you can write a
1 3
17. }, }
18.
3 9
proportion using the two ratios.
6 2
4 16
}, }
19. }, }
10 5
1 4
12 4
21. }, }
9 3
22.
}, }
6 4
6 4
1 5
23. }, }
2 10
24.
}, }
3 6
25. }, }
8 24
26.
}, }
5 10
1 1
3 15
27. }, }
4 20
28.
}, }
5, 8
29. }
}
5 8
30.
}, }
10 90
11 99
9 1
31. }, }
3 3
32.
}, }
Extend Your Skills
33. A seventh grade math class has 8 boys and 12 girls. An eighth grade math
class has 10 boys and 15 girls. For each class, write the ratio of boys to
girls. Can you write a proportion using these two ratios? Explain what this
means for the classes.
Puzzle
Shade each box in the first grid that
contains a fraction which forms a
4
proportion with }5. Shade each box
in the second grid that contains a
fraction which forms a proportion
2
with }3 . When done correctly, you
will form the two-digit number of
bathrooms in the White House.
}
32
40
}
28
35
}
}
12
16
}
50
40
}
}
15
20
}
36
45
}
}
8
12
}
28
30
}
40
50
}
16
20
}
}
70
8
9
McDougal Littell Middle School Math
Remediation Book Lesson 3.3
20
25
12
15
24
30
8
10
48
60
24
36
10
}
15
16
}
24
6
}
12
12
}
18
}
6
9
12
}
21
20
}
30
25
}
30
8
}
12
}
18
27
15
}
12
4
}
6
30
}
45
14
}
21
}
1 5
5 10
12 4
20 5
4 16
3 12
32 8
16 4
Copyright © by McDougal Littell, a division of Houghton Mifflin Company.
3. RATIO, PROPORTION
3. Writing Proportions
Write two different proportions using the given ratio.
!NSWER+EY
-iV̈œ˜ÊÎÊ,>̈œ]Ê*Àœ«œÀ̈œ˜]Ê>˜`Ê*iÀVi˜Ì
iÃܘÊÎÊ­««°ÊșÇä®
*À>V̈Vi\Ê
ˆÀÃÌÊ/ÀÞÊÊÊ
£°n°3AMPLEANSWERSAREGIVENÊÊÊ
£°]
z]
z]
z]
zÊÓ°]
z]
z]
z]
zÊΰ]
z]
z]
z]
zÊ{°]
z]
z]
z]
zÊx°]
z]
z]
z]
zÊ
È°]
z]
z]
z]
zÊÇ°]
z]
z]
z]zÊÊn°]
z]
z]
z]
zÊ
™°YESÊÊ£ä°NOÊÊÊ££°YESÊÊ£Ó°NOÊÊʣΰYESÊÊ£{°NOÊÊÊ£x°YESÊʣȰNO
-iVœ˜`Ê/ÀÞÊÊ
£°£È°3AMPLEANSWERSAREGIVENÊÊÊ
£°]
z]
z]
z]
zÊÊÓ°]z]z]z]zÊΰ]z]z]z]zÊ{°]z]z]z]zÊx°Ê]z]z]z]zÊ
È°]z]
z]z]zÊÇ°]z]z]z]zÊn°]z]z]z]zʙ°]z]z]z]zÊ£ä°]z]z]z]zÊ
££°]z]
z]z]z£Ó°]z]z]z]zʣΰ]z]z]z]z£{°]z]z]z]zÊÊ
£x°]z]
z]z]zʣȰ]z]z]z]z
£Ç°YESÊÊ£n°NOÊÊÊ£™°YESÊÊÓä°NOÊÊÊÓ£°YESÊÊÊÓÓ°YESÊÊÊ
ÓΰYESÊÊÓ{°NOÊÊÊÓx°NOÊÊÊÓÈ°NOÊÊÊÓÇ°YESÊÊÊ
Ón°YESÊÊә°YESÊÊÊÎä°YESÊÊΣ°NOÊÊÊÎÓ°YESÊÊÊ
Îΰ]
zOR]z]zOR]z YES4HECLASSESHAVETHESAMERATIOOFBOYSTOGIRLS
*Õââi