Ratios, Proportions

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Ratios, Proportions Rates
Do Now Write the following as percents. 4/10
.08 24/50
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Ratio

• A comparison of two quantities by division
• Ratios can compare two separate quantities
• Can be written 3 ways
• a to b
• a
• a b

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Example

• A family is decorating their Christmas tree. They
  want to put 3 strings of lights, 15 ornaments, 2
  strings of popcorn, and 1 star at the top.
• Write each ratio in all three forms.
• Ornaments to strings of lights
• Strings of lights to strings of popcorn
• Stars to total decorations to the tree

15 3 or 5 1
3 2, 3/2, 3 to 2
1 21, 1/21, 1 to 21
Does the order matter??
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Proportion

• Ratios that are equivalent
• Example

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Proportions

• Do the following sets of ratios form a
  proportion?
• 1 4
• 5 20
• 2 8
• 3 10

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Rate

• A ratio that compares two quantities measured in
  different units
• Jill ran 5 miles in 45 minutes

Unit Rate

• A rate in which the second quantity in the
  comparison is one unit
• Example 5 miles in 45 minutes ?
  
• Jill can run 1 mile in 9 minutes
• Unit rate a rate simplified to have a
  denominator of 1

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Example

• At Costco, you can buy a 10 pound bag of potatoes
  for 2.00.
• Write the rate that compares dollars to pounds
• Now write the unit rate (this answers the
  question How much does ONE pound cost?

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Which has a lower price?

• You can get 6 ounces for 1.29 or 15 ounces for
  3.00 Explain your answer (with math).
• 2 pounds of flour is 0.67. 10 pounds of flour is
  3.20. Explain your answer (with math).

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Rates Unit Rates

• For each situation, set up a rate, then find the
  unit rate.
• Unit rate How many____ in ONE _____ or
• How much _____ for ONE ______
• You can travel 15 miles in 3 hours.
• Milk costs 4.40 for 2 gallons.
• Matt can do 90 pushups in 3 minutes.
• Macys has a sale 4 shirts for 12.00.

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Assignment

• P. 344 9-16 and p. 348 1-10