Section D Practice Problems

Problem 1

There are 708 students in a school. There are 394 students in the cafeteria, and the rest are in class. Han estimates that 400 students are in class. Do you agree with Han’s estimate? Explain or show your reasoning.

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Solution

No. Sample response: There are about 700 students at the school and about 400 are in the cafeteria. The rest, about 300, are in class.

Problem 2

Select all equations that match the diagram.

Diagram. One rectangle split into 6 parts. Total length, 110. 1 part, labeled question mark. Other 5 parts labeled 6.

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Solution
B,C,E

Problem 3

There are 240 connecting cubes in the box. Five students each take 9 connecting cubes from the box. How many connecting cubes are left in the box?

  1. Write an equation to represent the situation. Use a letter for the unknown quantity.
  2. Solve the problem. Explain or show your reasoning.
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Solution
  1. Sample response: 240−(5×9)=?240 - (5 \times 9) = {?}
  2. 195 connecting cubes. Sample response: 5×9=455 \times 9 = 45 and 240−45=195240 - 45 = 195

Problem 4

Andre had 245 cards. He buys 7 packages of cards.

  1. What information do you need to know to find the number of cards Andre has now?
  2. Write an expression to represent the number of cards Andre has now. Use a letter for the unknown quantity.
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Solution

Sample response:

  1. How many cards are in each package?
  2. If cc is the number of cards in each package, then Andre has 245+7×c245 + 7 \times c cards.

Problem 5

For each equation, draw a diagram and write a situation with a question.

  1. (3×n)+163=187(3 \times n) + 163 = 187
  2. b−(4×10)=89b - (4 \times 10) = 89
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Solution

Sample responses:

  1.  
    Diagram.
    There were 163 kids at the water park. Then 3 vans arrived carrying the same number of kids. Now there are 187 kids at the water park. How many kids were in each van? 
  2.  
    Diagram.
    Jada picked a lot of oranges. She filled 4 bags each with 10 oranges, and still had 89 oranges left. How many oranges did Jada pick?

Problem 6

  1. A question in a subtraction situation can be answered with an estimate of “about 200.” What could be the subtraction situation?
  2. A question in a situation that uses multiplication and addition could be answered with an estimate of “about 300.” What could be the situation?
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Solution
Sample responses:
  1. We drove 612 miles this weekend. We drove 395 miles on Sunday. How many miles did we drive on Saturday?
  2. Diego’s class had 204 markers. They got 9 more packs of markers. Each pack had 10 markers. How many markers does Diego's class have now?