Lesson 12
Negative Rates
Problem 1
Describe a situation where each of the following quantities might be useful.
 20 gallons per hour
 10 feet per minute
 0.1 kilograms per second
Solution
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Problem 2
A submarine is only allowed to change its depth by rising toward the surface in 60meter stages. It starts off at 340 meters.

At what depth is it after:
 1 stage
 2 stages
 4 stages
 How many stages will it take to return to the surface?
Solution
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Problem 3
Some boats were traveling up and down a river. A satellite recorded the movements of several boats.
 A motor boat traveled 3.4 miles per hour for 0.75 hours. How far did it go?
 A tugboat traveled 1.5 miles in 0.3 hours. What was its velocity?
 What do you think that negative distances and velocities could mean in this situation?
Solution
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Problem 4
 A cookie recipe uses 3 cups of flour to make 15 cookies. How many cookies can you make with this recipe with 4 cups of flour? (Assume you have enough of the other ingredients.)
 A teacher uses 36 centimeters of tape to hang up 9 student projects. At that rate, how much tape would the teacher need to hang up 10 student projects?
Solution
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(From Unit 4, Lesson 3.)Problem 5
Evaluate each expression. When the answer is not a whole number, write your answer as a fraction.
 \(\text4 \boldcdot \text6\)
 \(\text24 \boldcdot \frac {\text{}7}{6}\)
 \(4 \div \text6\)
 \(\frac43 \div \text24\)
Solution
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(From Unit 5, Lesson 11.)