Lesson 6.2Division Expressions with Fractions and Mixed Numbers
Set B · Version ASecond form · supported practice
Learning target I can explain what dividing a fraction by a fraction means, find the quotient with common denominators or by multiplying by the reciprocal, and check it by multiplying.
Why This Matters Agent Rivera is dividing a 3/4-pound evidence bag into portions that each weigh 1/8 pound. She needs to know exactly how many portions she can make for testing. Can you solve the case?
RememberDivision Expressions with Fractions and Mixed Numbers
Dividing Fractions by Fractions. Formula: a/b ÷ c/d = a/b × d/c When you divide a fraction by a fraction, you keep the first fraction, change ÷ to ×, and flip the second fraction (the divisor) to its reciprocal. Then multiply and simplify.
- Name the question: 3/4 ÷ 1/8 asks how many 1/8s fit in 3/4.
- Use common denominators: 3/4 = 6/8, and 6 eighths ÷ 1 eighth =
- Shortcut: multiply by the reciprocal of the divisor, 3/4 × 8/1 = 24/4 = 6, then check by multiplying: 6 × 1/8 = 6/8 = 3/4
Words: Dividend (Dividendo)Divisor (Divisor)Reciprocal (Recíproco)Quotient (Cociente)Simplify (Simplificar)
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1Circle the letter of the best answer. Show how you know.
What is 6 ÷ 1/2?
- A1/12
- B3
- C6 1/2
- D12
Show your work -
2Circle the letter of the best answer. Show how you know.
What is 6 ÷ 1/3?
- A2
- B3
- C1/18
- D18
Show your work -
3Circle the letter of the best answer. Show how you know.
What is 3 ÷ 1/5?
- A3/5
- B5/3
- C8
- D15
Show your work -
4Circle the letter of the best answer. Show how you know.
What is 10 ÷ 1/4?
- A2.5
- B1/40
- C14
- D40
Show your work
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5Circle the letter of the best answer. Show how you know.
The lab printer fills 2/5 of a box of evidence labels in 1/2 hour. At that rate, how much of a box does it fill in ONE hour?
- A1/5 box
- B1 1/4 boxes
- C4/5 box
- D9/10 box
Hint How many half-hours are in one hour?
Show your work
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6Find the mistake. Explain it, then show the correct work.
Spot the Common Mistake
- 1Problem1/2 ÷ 1/4
- 2Divide straight across(1 ÷ 1) / (2 ÷ 4) = 1/(1/2)
- 3Answer= 2
Which step has the mistake? Explain what went wrong, then show the correct work.
Hint You cannot divide fractions by dividing the numerators and denominators straight across.
Correct workCorrect answer:
Explain your thinkingWhy does 5/6 ÷ 1/12 = 10? How does the bar model show this?
Sentence starter 5/6 ÷ 1/12 = 10 because 5/6 is the same as ___ twelfths, and ___ twelfths divided by 1 twelfth = ___.
Lesson 6.2Division Expressions with Fractions and Mixed Numbers
Set B · Version BSecond form · core practice
Learning target I can explain what dividing a fraction by a fraction means, find the quotient with common denominators or by multiplying by the reciprocal, and check it by multiplying.
Why This Matters Agent Rivera is dividing a 3/4-pound evidence bag into portions that each weigh 1/8 pound. She needs to know exactly how many portions she can make for testing. Can you solve the case?
-
1Circle the letter of the best answer. Show how you know.
What is (3/4) ÷ (1/2)?
- A1/2
- B2/3
- C3/2
- D3/8
Write any whole number over 1Keep · Change · FlipMultiply acrossSimplify · label the units -
2Circle the letter of the best answer. Show how you know.
What is (2/3) ÷ (4/9)?
- A2/3
- B3/2
- C8/27
- D9/4
Write any whole number over 1Keep · Change · FlipMultiply acrossSimplify · label the units -
3Circle the letter of the best answer. Show how you know.
What is (5/6) ÷ (5/12)?
- A1/2
- B2
- C12/5
- D25/72
Write any whole number over 1Keep · Change · FlipMultiply acrossSimplify · label the units
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4Circle the letter of the best answer. Show how you know.
A carpenter has a board that is 5/6 of a foot long. She needs to cut pieces that are each 1/12 of a foot. She wants to know how many pieces she can cut from the board. 5/6 ÷ 1/12 = ?
- A2
- B5/72
- C10
- D12
Show your work -
5Circle the letter of the best answer. Show how you know.
A carpenter has a board that is 5/6 of a foot long. She needs to cut pieces that are each 1/12 of a foot. She wants to know how many pieces she can cut from the board. Rewrite 5/6 with a denominator of 12.
- A5/12
- B6/12
- C10/12
- D11/12
Write any whole number over 1Keep · Change · FlipMultiply acrossSimplify · label the units -
6Circle the letter of the best answer. Show how you know.
A carpenter has a board that is 5/6 of a foot long. She needs to cut pieces that are each 1/12 of a foot. She wants to know how many pieces she can cut from the board. If each piece were 1/6 of a foot, how many pieces?
- A5
- B6
- C10
- D30
Write any whole number over 1Keep · Change · FlipMultiply acrossSimplify · label the units