Basic Mathematics for College Students

Solve application problems by adding and subtracting

fractions.

5

250 Chapter 3 Fractions and Mixed Numbers

Self Check 11

Refer to the circle graph for

Example 11. Find the fraction

of the student body that

watches 2 or more hours

of television daily.

Now TryProblems 65 and 109

Self Check 10

Which fraction is larger:

or

Now TryProblem 61

3

5

?

7

12

EXAMPLE 10

Which fraction is larger: or

Strategy We will express each fraction as an equivalent fraction that has the LCD

for its denominator. Then we will compare their numerators.

WHY We cannot compare the fractions as given. They are not similar objects.

five-sixths seven-eighths

Solution

Since the smallest number the denominators will divide exactly is 24, the LCD for

and is 24.

To build and so that their denominators

are 24, multiply each by a form of 1.

Multiply the numerators.

Multiply the denominators.

Next, we compare the numerators. Since 21 20, it follows that is greater than

2420. Thus,^78  65.

21

24



21

24



20

24

7

8

5

7 6

8



7

8



3

3

5

6



5

6



4

4

7

8

5

6

 

7

8

?

5

6

EXAMPLE (^11) Television Viewing Habits Students on a college
campus were asked to estimate to the nearest hour how much television they
watched each day. The results are given in the circle graphbelow (also called a
pie chart). For example, the chart tells us that of those responding watched
1 hour per day. What fraction of the student body watches from 0 to 2 hours
daily?
Analyze

• of the student body watches no TV daily. Given


• of the student body watches 1 hour of TV daily. Given


• of the student body watches 2 hours of TV daily. Given


• What fraction of the student body watches 0 to 2 hours of TV daily?Find
  Form We translate the words of the problem to numbers and symbols.

is equal to plus plus

=++

7

15

1

4

1

6

The fraction

of the student

body that

watches from

0 to 2 hours

of TV daily

the fraction

that watches

2 hours of

TV daily.

the fraction

that watches

1 hour of

TV daily

the fraction

that watches

no TV daily

The fraction

of the student

body that

watches from

0 to 2 hours

of TV daily

7

15

1

4

1

6

1

4

1 hour

2 hours

3 hours

4 or more

No TV hours

(^1) –
4
(^1) –
6
––^7
15
––^1
12
––^1
30