Grade 7, Unit 3 Practice Problems - Open Up Resources

1 ( )( ) Grade 7 Math(/7/ )Units(/7/ )Teacher Guide(/7/ )PrAssessmentsachers/3/ ) Practice Problems (/7/teachers/3 ) unit Downloads(/7/teachers/3 3 PracticeProblemsUnit 3 Practice ProblemsLesson 1 Lesson 2 Lesson 3 Lesson 4 Lesson 5 Lesson 6 Lesson 7 Lesson 8 Lesson 9 Lesson 10 Lesson 1 Problem 1 Estimate the side length of a square that has a 9 cm long cm, because the perimeter of the square is approximately or cm and 2 Select all quantities that are proportional to the diagonal length of a Area of a squareB.

2 Perimeter of a squareC. Side length of a squareSolutionB, CProblem 3 Diego made a graph of two quantities that he measured and said, The points all lie on aline except one, which is a little bit above the line. This means that the quantities can t beproportional. Do you agree with Diego? vary. Sample response: I don t agree with Diego, since the quantities could beproportional if the line goes through the origin. Measurements are not perfect and therelationship could be 4 The graph shows that while it was being lled, the amount of water in gallons in aswimming pool was approximately proportional to the time that has passed in About how much water was in the pool after 25 minutes?

3 2. Approximately when were there 500 gallons of water in the pool?3. Estimate the constant of proportionality for the number of gallons of water perminute going into the About 380 gallons2. After about 35 minutes3. About 15 Lesson 2 Problem 1 Use a geometric tool to draw a circle. Draw and measure a radius and a diameter of 2 Here is a circle with center and some line segments and curves joining points on examples of the following. Explain your Diameter2. RadiusSolution1. Segments and.

4 They are line segments that go through the center of the circlewith endpoints on the Segments , , , and are radii. They are line segments that go from thecenter to the 3 Lin measured the diameter of a circle in two di erent directions. Measuring vertically, shegot cm, and measuring horizontally, she got cm. Explain some possible reasons whythese measurements di diameters of a circle should have the same length. Explanations vary. Possibleexplanations:These measurements could be rounded, not thickness of the circle could have a ected the did not measure across the widest part when measuring shape is not quite a circle, because a perfect circle is very hard to 4(from unit 2, Lesson 1)A small, test batch of lemonade used cup of sugar added to 1 cup of water and cup oflemon juice.

5 After con rming it tasted good, a larger batch is going to be made with thesame ratios using 10 cups of water. How much sugar should be added so that the largebatch tastes the same as the test batch? cups since the larger batch is 10 times larger (for the water ) and .Problem 5(from unit 2, Lesson 13)The graph of a proportional relationship contains the point with coordinates . What isthe constant of proportionality of the relationship?Solution4 Lesson 3 Problem 1 Diego measured the diameter and circumference of several circular objects and recordedhis measurements in the (cm)circumference (cm)half dollar coin310 ying disc2328jar lid825 ower pot1548 One of his measurements is inaccurate.

6 Which measurement is it? Explain how you measurement for the ying disc is very inaccurate. It should be about 3 times thediameter (or a little more).Problem 2 Complete the table. Use one of the approximate values for discussed in class (forexample , , ). Explain or show your hoop35 in circular pond 556 ftmagnifying cm car tire in Solutionobjectdiametercircumferencehula hoop35 in110 incircular pond177 ft556 ftmagnifying cm16 cmcar inThe constant of proportionality is about The given diameters are multiplied by to nd the missing circumferences.

7 The given circumferences are divided by to nd themissing diameters. Both the missing circumferences and the missing diameters have 3(from unit 3, Lesson 2)1. Name a segment that is a radius. How long is it?2. Name a segment that is a diameter. How long is it?Solution1. Answers vary. Sample responses: , , , , , cm2. CD, 15 cmProblem 4(from unit 2, Lesson 10)1. Consider the equation . Find four pairs of and values that make theequation true. Plot the points on the coordinate Based on the graph, can this be a proportional relationship?

8 Why or why not?Solution1. Answers vary. Sample response: 2. Answers vary. Sample response: No, this relationship could not be proportionalbecause the graph does not go through .Lesson 4 Problem 1 Here is a picture of a ferris wheel . It has a diameter of 80 On the picture, draw and label a How far does a rider travel in one complete rotation around the ferris wheel ?Solution1. Answers vary. Possible response:2. In one complete rotation, a rider travels the circumference of the ferris wheel . Thisdistance is , or about 251 meters.

9 Since the gondola where the rider is seated isa little bit further from the center of the ferris wheel than 40 meters, the distance therider travels is actually a little 2 Identify each measurement as the diameter, radius, or circumference of the circular , estimate the other two measurements for the The length of the minute hand on a clock is 5 The distance across a sink drain is The tires on a mining truck are 14 ft The fence around a circular pool is 75 ft The distance from the tip of a slice of pizza to the crust is 7 Breaking a cookie in half creates a straight side 10 cm The length of the metal rim around a glass lens is 190 From the center to the edge of a DVD measures 60 Radius.

10 Diameter: 10 in, circumference: about 31 in2. Diameter; radius: cm, circumference: about 12 cm3. Diameter; radius: 7 ft, circumference: about 44 ft4. Circumference; diameter: about 24 ft, radius: about 12 ft5. Radius; diameter: 14 in, circumference: about 44 in6. Diameter; radius: 5 cm, circumference: about 31 cm7. Circumference; diameter: about 60 mm, radius: about 30 mm8. Radius; diameter: 120 mm, circumference: about 380 mmProblem 3A half circle is joined to an equilateral triangle with side lengths of 12 units.