Student Resources—746
Student Resources—746
Student Resources—746
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Math Skill Handbook<br />
Math Skill Handbook<br />
Use Fractions<br />
A fraction compares a part to a whole. In<br />
the fraction 2<br />
, the 2 represents the part and<br />
3<br />
is the numerator. The 3 represents the whole<br />
and is the denominator.<br />
Reduce Fractions To reduce a fraction, you<br />
must find the largest factor that is common to<br />
both the numerator and the denominator, the<br />
greatest common factor (GCF). Divide both<br />
numbers by the GCF. The fraction has then<br />
been reduced, or it is in its simplest form.<br />
Example Twelve of the 20 chemicals in the science<br />
lab are in powder form.What fraction of the<br />
chemicals used in the lab are in powder form?<br />
Step 1 Write the fraction.<br />
part<br />
<br />
whole<br />
12<br />
<br />
20<br />
Step 2 To find the GCF of the numerator and denominator,<br />
list all of the factors of each number.<br />
Factors of 12: 1, 2, 3, 4, 6, 12 (the numbers<br />
that divide evenly into 12)<br />
Factors of 20: 1, 2, 4, 5, 10, 20 (the numbers<br />
that divide evenly into 20)<br />
Step 3 List the common factors.<br />
1, 2, 4.<br />
Step 4 Choose the greatest factor in the list.<br />
The GCF of 12 and 20 is 4.<br />
Step 5 Divide the numerator and denominator by<br />
the GCF.<br />
12<br />
4<br />
<br />
20<br />
4<br />
3<br />
5 <br />
In the lab, 3<br />
of the chemicals are in powder form.<br />
5<br />
Practice Problem At an amusement park, 66 of 90<br />
rides have a height restriction.What fraction of the<br />
rides, in its simplest form, has a height restriction?<br />
776 STUDENT RESOURCES<br />
Math Review<br />
Add and Subtract Fractions To add or<br />
subtract fractions with the same denominator,<br />
add or subtract the numerators and<br />
write the sum or difference over the denominator.<br />
After finding the sum or difference,<br />
find the simplest form for your fraction.<br />
Example 1 In the forest outside your house, 1<br />
of the<br />
8<br />
animals are rabbits, 3<br />
are squirrels, and the remainder<br />
8<br />
are birds and insects. How many are mammals?<br />
Step 1 Add the numerators.<br />
1 3)<br />
3 (1 <br />
8 8 8<br />
4<br />
8 <br />
Step 2 Find the GCF.<br />
4<br />
(GCF, 4)<br />
8<br />
Step 3 Divide the numerator and denominator by<br />
the GCF.<br />
4<br />
1, 8 2<br />
4 4<br />
1<br />
of the animals are mammals.<br />
2<br />
7<br />
Example 2 If of the Earth is covered by<br />
16<br />
1<br />
freshwater, and of that is in glaciers, how much<br />
16<br />
freshwater is not frozen?<br />
Step 1 Subtract the numerators.<br />
7 1 (7 1) 6<br />
16<br />
16<br />
16 16<br />
Step 2 Find the GCF.<br />
6<br />
(GCF, 2)<br />
16<br />
Step 3 Divide the numerator and denominator by<br />
the GCF.<br />
6 6<br />
3, 1 8<br />
2 2<br />
3<br />
of the freshwater is not frozen.<br />
8<br />
Practice Problem A bicycle rider is going 15 km/h<br />
for 4<br />
of his ride, 10 km/h for 2 of his ride, and 8 km/h<br />
9 9<br />
for the remainder of the ride. How much of his ride is<br />
he going over 8 km/h?
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