Lesson 17
Modeling with Inequalities
Problem 1
28 students travel on a field trip. They bring a van that can seat 12 students. Elena and Kiran’s teacher asks other adults to drive cars that seat 3 children each to transport the rest of the students.
Elena wonders if she should use the inequality \(12+3n>28\) or \(12+3n\geq28\) to figure out how many cars are needed. Kiran doesn’t think it matters in this case. Do you agree with Kiran? Explain your reasoning.
Solution
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Problem 2
- In the cafeteria, there is one large 10-seat table and many smaller 4-seat tables. There are enough tables to fit 200 students. Write an inequality whose solution is the possible number of 4-seat tables in the cafeteria.
- 5 barrels catch rainwater in the schoolyard. Four barrels are the same size, and the fifth barrel holds 10 liters of water. Combined, the 5 barrels can hold at least 200 liters of water. Write an inequality whose solution is the possible size of each of the 4 barrels.
- How are these two problems similar? How are they different?
Solution
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Problem 3
Solve each equation.
- \(5(n-4)=\text-60\)
- \(\text-3t+ \text-8=25\)
- \(7p-8=\text-22\)
- \(\frac25(j+40)=\text-4\)
- \(4(w+1)=\text-6\)
Solution
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(From Unit 6, Lesson 9.)Problem 4
Select all the inequalities that have the same graph as \(x<4\).
\(x<2\)
\(x+6<10\)
\(5x<20\)
\(x-2>2\)
\(x<8\)
Solution
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(From Unit 6, Lesson 13.)Problem 5
A 200 pound person weighs 33 pounds on the Moon.
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How much did the person’s weight decrease?
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By what percentage did the person’s weight decrease?
Solution
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(From Unit 4, Lesson 12.)