KEY
LESSON: WHAT IS A RATIO? (continued)
Come up with two examples of ratio relationships that are interesting to you.
Verbal clues: “to” , “for each” , “for every”
Example:
For every 2 chores my mom gives my brother, she gives 3 to me. The ratio is 2:3 or 2 to 3
2
or .
3
At a t-shirt manufacturing company surveyed teenaged girls on their favorite t-shirt color
to guide the company’s decision about how many of each color t-shirt they should design
and manufacture;. The results are shown here.
Favorite T-shirt Colors of Teenaged Girls Surveyed
X
X
X
X
X
Red
Blue
X
X
Green
X
X
X
X
X
X
X
X
X
X
X
X
White
Pink
X
X
X
Orange
X
X
X
X
Yellow
1. Describe a ratio relationship, in the context of this survey, for which the ratio is 3:5.
Orange has 3 and Pink has 5, so 3:5 is Orange:Pink.
Are the ratios 2:5 and 5:3 the same? Why or why not? No, they are not because order
matters in ratios!!!!!
Lesson Summary:
* Ratios can be written in three ways: A to B , A:B , or A
B
* Keep words for ratios: for each, for every, and to.
* The ratio A:B is not the same as the ratio B:A (unless A is equal to B).
ORDER MATTERS!
Math 6
9/18/13 HW
Problem Set:
1. Using the floor tiles design shown below, create 4 different ratios related to the image.
Describe the ratio relationship and write the ratio in the form A:B or the form A to B.
a.
b.
c.
d.
white
white
white
black
tiles
tiles
tiles
tiles
to
to
to
to
black tiles: 4:2 (can be reduced to 2:1)
gray tiles: 4:10 (can be reduced to 2:5)
total tiles: 4:16 (can be reduced to 1:4)
gray tiles: 2:10 (can be reduced to 1:5)
2. Billy wanted to write a ratio of the number of cars to the number of trucks in the police
parking lot. He wrote 1:3. Did Billy write the ratio correctly? Explain your answer.
There are 3 cars and 1 truck. The ratio asks for cars to trucks, so the ratio
should be 3:1, not 1:3. Billy was not correct.
Task:
A. Mr. Black’s class has a female student to male student ratio of 3:2. If Mr. Black’s class
has 18 girls, how many boys does he have? Explain in writing how you determined your
answer.
3 females to 2 males
12 males
18 females
B. Ms. Green’s class has the same number of students as Mr. Black’s class. Her female to
male ratio is 2:1. Which class has the greater number of females? How do you know?
Mr. Black’s class has a total of 30 students (18 + 12 = 30).
2 females to
20 females
1 males
10 males
Ms. Green’s class has the same number of students as Mr. Black’s class,
30 students, except her ratio of female to male is 2:1.