Five-Minute Check (over Lesson 2–2)

Main Idea and Vocabulary

Key Concept: Multiply Fractions

Example 1:Multiply Positive Fractions

Example 2:Multiply Negative Fractions

Example 3:Multiply Mixed Numbers

Example 4:Real-World Example

Example 5:Use Dimensional Analysis

• dimensional analysis

• Multiply positive and negative fractions.

The process of including units of measurement when you compute.

Animation:Multiplying Fractions

Multiply Positive Fractions

Answer:

Simplify.

Multiply the numerators.Multiply the denominators.

Divide 3 and 9 by their GCF, 3.3

1

1. A

2. B

3. C

4. D0% 0%0%0%

A.

B.

C.

D.

Multiply Negative Fractions

Divide –3 and 12 by their GCF, 3.

The numerator and denominator have different signs, so the product is negative.

Multiply the numerators.Multiply the denominators.

Answer:

1. A

2. B

3. C

4. D0% 0%0%0%

A.

B.

C.

D.

Multiply Mixed Numbers

Divide 16 and 4 by their GCF, 4.

Multiply the numerators.Multiply the denominators.

Estimate 3 × 2 = 6.

Multiply Mixed Numbers

Answer:

Simplify. Compare to the estimate.

1. A

2. B

3. C

4. D0% 0%0%0%

A.

B.

C.

D.

VOLUNTEER WORK Last summer, the 7th graders

performed a total of 250 hours of community service.

If the 8th graders spent this much time

volunteering, how many hours of community service

did the 8th graders perform?

The 8th graders spent the amount of time as the

7th graders on community service.

Answer: The 8th graders did 300 hours of community service last summer.

1. A

2. B

3. C

4. D0% 0%0%0%

A. 175 hours B. 190 hours

C. 200 hours D. 225 hours

VOLUNTEER WORK Last summer, the 5th graders

performed a total of 150 hours of community service.

If the 6th graders spent this much time

volunteering, how many hours of community service

did the 6th graders perform?

Use Dimensional Analysis

WATER USE Low–flow showerheads use gallons

of water per minute. If family members shower a total

of hours per week, how much water does the

family use for showers each week?

Words Water used equals the time multiplied by the water flow rate.

Variable Let w represent the gallons of water used.

Equation

Divide by common factors and units.

Use Dimensional Analysis

Use Dimensional Analysis

Answer: If the family showers hours per week at a

rate of gallons per minute, they will use

350 gallons of water.

1. A

2. B

3. C

4. D

A. 15 gallons B. 38 gallons

C. 775 gallons D. 897 gallons 0% 0%0%0%

End of the Lesson

Five-Minute Check (over Lesson 2–2)

Image Bank

Math Tools

Multiplying Fractions

Multiplying and Dividing Fractions

1. A

2. B

3. C0% 0%0%

A. <

B. >

C. =

(over Lesson 2-2)

Use <, >, or = to make a true sentence.

1. A

2. B

3. C0% 0%0%

A. <

B. >

C. =

(over Lesson 2-2)

Use <, >, or = to make – –4.46 a true sentence.

1. A

2. B

3. C0% 0%0%

A. <

B. >

C. =

(over Lesson 2-2)

Use <, >, or = to make a true sentence.

1. A

2. B

3. C

4. D0% 0%0%0%

(over Lesson 2-2)

A.

B.

C.

D.

1. A

2. B

3. C

4. D0% 0%0%0%

(over Lesson 2-2)

A.

B.

C.

D.

1. A

2. B

3. C

4. D0% 0%0%0%

Which number is least?

(over Lesson 2-2)

A.

B. 0.83

C.

D. 0.61