Answers:
- Expression is [tex]15 \frac{1}{4} \div 4 \frac{3}{4}[/tex]
- whole number = 3
- fractional part = 4/19
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Explanation:
Let's convert the mixed number [tex]15 \frac{1}{4}[/tex] to an improper fraction
[tex]a \frac{b}{c} = \frac{a*c+b}{c}\\\\15 \frac{1}{4} = \frac{15*4+1}{4}\\\\15 \frac{1}{4} = \frac{61}{4}\\\\[/tex]
Do the same for the other mixed number.
[tex]a \frac{b}{c} = \frac{a*c+b}{c}\\\\4 \frac{3}{4} = \frac{4*4+3}{4}\\\\4 \frac{3}{4} = \frac{19}{4}\\\\[/tex]
We'll divide those two improper fractions to find the number of pieces
[tex]15 \frac{1}{4} \div 4 \frac{3}{4}\\\\\frac{61}{4} \div \frac{19}{4}\\\\\frac{61}{4} \times \frac{4}{19}\\\\\frac{61}{19}\\\\[/tex]
Then let's convert that to a mixed number like so:
[tex]\frac{61}{19}=\frac{57+4}{19}\\\\\frac{61}{19}=\frac{57}{19}+\frac{4}{19}\\\\\frac{61}{19}=3+\frac{4}{19}\\\\\frac{61}{19}=3\frac{4}{19}\\\\[/tex]
Or you could note that 61/19 leads to 3 remainder 4.
The carpenter is able to get 3 whole pieces out, then the extra fractional part is 4/19 of a foot.
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Here's another way to look at it.
Grab a footlong ruler and split it into 4 equal smaller lengths. I'll refer to these smaller pieces as "quarters" from now on.
1 ruler = 4 quarters
15 rulers = 15*4 = 60 quarters
15 rulers + 1 quarter = 60+1 = 61 quarters
So this is another way to see how the mixed number [tex]15 \frac{1}{4}[/tex] is the same as the improper fraction [tex]\frac{61}{4}[/tex]
The same idea would apply to [tex]4 \frac{3}{4} = \frac{19}{4}\\\\[/tex]
The overall entire board is 61 quarters long, and each piece is 19 quarters long. So that means 61/19 = 3 & 4/19 represents the number of pieces we can cut.