Transcript Grade 6- 8-1 Notes

Objective:
Students will express ratios and
rates as fractions (8-1).
Vocabulary:
• Rate- a ratio of two measurements
that have different units.
• Ratio- comparison of two numbers by
division
Ratio as a fraction:
• Read all directions!!!!!
• Write the problem down.
• Write the ratio as a fraction. The
first # = the numerator. The second
# = the denominator.
• Last, simplify.
Ratio as a rate:
• Read all directions!!!!!
• Write down the problem.
• Write problem as a fraction (fraction
may be a improper fraction).
• Divide denominator into numerator in
order to simplify.
• Be careful when working with money.
Notes:
• A ratio can be written 4 ways:
24 to 108
24 out of 108
24:108
24 over 108 (fraction)
Examples
• Express the ratio that compares the
number of strawberries to the total
number of pieces of fruit as a fraction in
simplest form.
Strawberries
4
Examples
• Express the ratio that compares the
number of strawberries to the total
number of pieces of fruit as a fraction in
simplest form.
Strawberries
Pieces of fruit
4
10
Examples
• Express the ratio that compares the
number of strawberries to the total
number of pieces of fruit as a fraction in
simplest form.
Strawberries
Pieces of fruit
4 =2
10 = 5
Examples
• Express the ratio that compares the number of
strawberries to the total number of pieces of
fruit as a fraction in simplest form.
Strawberries
Pieces of fruit
4 =2
10 = 5
The GCF of 4 and
10 is 2. Divide the
numerator and the
denominator by the
GCF 2.
The ratio in simplest form is 2
5
• Express the ratio 7 inches of
rain in 28 days as a rate.
7 inches
• Express the ratio 7 inches of
rain in 28 days as a rate.
7 inches
28 days
• Express the ratio 7 inches of rain in 28
days as a rate.
•
7 inches = 0.25 inch
28 days = 1 day
Divide the numerator and the
denominator by 28 to get a denominator of
1.
The total rain fall is equivalent
to 0.25 inch each day.
• Dhara purchased a 14.5 ounce bag of
chips for $3.19. What was the cost per
ounce?
Explore You know that the 14.5 ounce
bag of chips costs $3.19 You
need to find the cost per
ounce.
Plan
Use a rate to compare the cost
to the weight.
Solve
$3.19 = $0.22
14.5 oz. = 1 oz.
Divide the numerator and the
denominator by 14.5 to get a
denominator of 1.
3.19 ÷ 14.5 = 0.22
The cost is 22 cents per ounce.
Examine $0.22 x 14.5 = $3.19 So the
answer is correct.
Guided Practice
Write each ratio in three different ways:
• 7 carnations out of 24 flowers
• 15 mint chip cookies in a bag of 34 cookies
Write each ratio in three different ways:
• 7 carnations out of 24 flowers
7 out of 24
7 to 24
7:24
• 15 mint chip cookies in a bag of 34 cookies
15 to 34
15 out of 34
15
34
Express each ratio as a fraction in
simplest from:
• 16 beagles out of 24 dogs
• 10 emeralds out of 25 gems
Express each ratio as a fraction in simplest
from:
• 16 beagles out of 24 dogs
16 beagles = 2 beagles
24 dogs = 3 dogs
• 10 emeralds out of 25 gems
10 emeralds = 2 emeralds
25 gems
= 5 gems
Express each ratio as a rate:
• 120 words in 3 minutes
• 5 soft drinks for $3.25
• The fastest running bird is the ostrich. An
ostrich can run 240 miles in 6 hours. What is
the average speed of an ostrich?
Express each ratio as a rate:
• 120 words in 3 minutes
120 words = 40 words
3 minutes = 1 min.
The answer is 40 words per minute.
• 5 soft drinks for $3.25
$3.25
=
$0.65
5 soft drinks = 1 soft drink
The answer is $0.65 per soft drink.
• The fastest running bird is the
ostrich. An ostrich can run 240 miles
in 6 hours. What is the average
speed of an ostrich?
240 miles = 40 miles
6 hours = 1 hour
The answer is 40 miles per hour.