For each of the questions below, choose the expression that describes the solution. Class 7

For each of the questions below, choose the expression that describes the solution. Class 7

Question 1.

For each of the questions below, choose the expression that describes the solution. Then simplify it.

(a) Maria bought 8 m of lace to decorate the bags she made for school. She used [latex]\frac {1}{4}[/latex] m for each bag and finished the lace. How many bags did she decorate?

(i) 8 × [latex]\frac {1}{4}[/latex]

(ii) [latex]\frac {1}{8}[/latex] × [latex]\frac {1}{4}[/latex]

(iii) 8 ÷ [latex]\frac {1}{4}[/latex]

(iv) [latex]\frac {1}{4}[/latex] ÷ 8

Solution:

Correct expression is (iii) 8 ÷ [latex]\frac {1}{4}[/latex]

Now, 8 ÷ [latex]\frac {1}{4}[/latex] = 8 × [latex]\frac {4}{1}[/latex] = 32

So, she decorated 32 bags.

(b) [latex]\frac {1}{2}[/latex] metre of ribbon is used to make 8 badges. What is the length of the ribbon used for each badge?

(i) 8 × [latex]\frac {1}{2}[/latex]

(ii) [latex]\frac {1}{2}[/latex] ÷ [latex]\frac {1}{8}[/latex]

(iii) 8 ÷ [latex]\frac {1}{2}[/latex]

(iv) [latex]\frac {1}{2}[/latex] ÷ 8

Solution:

Correct expression is (iv) [latex]\frac {1}{2}[/latex] ÷ 8

So, length of the ribbon used for each badge

[latex]\frac {1}{2}[/latex] ÷ 8 = [latex]\frac {1}{2}[/latex] × [latex]\frac {1}{8}[/latex] = [latex]\frac{1 \times 1}{2 \times 8}[/latex] = [latex]\frac {1}{16}[/latex] m

(c) A baker needs [latex]\frac {1}{6}[/latex] kg of flour to make one loaf of bread. He has 5 kg of flour. How many loaves of bread can he make?

(i) 5 × [latex]\frac {1}{6}[/latex]

(ii) [latex]\frac {1}{6}[/latex] ÷ 5

(iii) 5 ÷ [latex]\frac {1}{6}[/latex]

(iv) 5 × 6

Solution:

Correct expression is (iii) 5 ÷ [latex]\frac {1}{6}[/latex]

So, number of loaves of bread that can he make

5 ÷ [latex]\frac {1}{6}[/latex] = 5 × [latex]\frac {6}{1}[/latex] = 30.

Question 2.

If [latex]\frac {1}{4}[/latex] kg of flour is used to make 12 rotis, 4 how much flour is used to make 6 rotis? Class 7

Solution:

For 12 rotis, flour required = [latex]\frac {1}{4}[/latex] kg.

So, for 1 roti, flour required = [latex]\frac {1}{4}[/latex] ÷ 12 kg.

= [latex]\frac {1}{4}[/latex] × [latex]\frac {1}{12}[/latex] kg = [latex]\frac {1}{48}[/latex] kg

Hence, for 6 rotis, flour required

= [latex]\frac {1}{48}[/latex] × 6 kg = [latex]\frac {6}{48}[/latex] = [latex]\frac {1}{8}[/latex] kg