Page 240 - Basic College Mathematics with Early Integers

S E C T I O N 3.4 I ADDING AND SUBTRACTING LIKE FRACTIONS, LEAST COMMON DENOMINATOR 217

Solve. For Exercises 47 and 48, the solutions have been started for you.Write each answer in simplest form.
See Example 11.
19 11
47. A railroad inspector must inspect of a mile of 48. Scott Davis has run miles already and plans to
20 8
5 16
railroad track. If she has already inspected of a mile, complete miles. To do this, how much farther must
20 8
how much more does she need to inspect? he run?
Start the solution: Start the solution:
1. UNDERSTAND the problem. Reread it as many 1. UNDERSTAND the problem. Reread it as many
times as needed. times as needed.
2. TRANSLATE into an equation. (Fill in the blanks.) 2. TRANSLATE into an equation. (Fill in the blanks.)

distance distance distance distance distance distance
left to is needed to minus already left to is planned minus already
inspect inspect inspected run to run run
T T T T T T T T T T

distance distance
left to = - left to = -
inspect run
Finish with: Finish with:
3. SOLVE. and 4. INTERPRET. 3. SOLVE. and 4. INTERPRET.
31
49. As of 2009, the fraction of states in the United 50. When people take aspirin, of the time it is used to
50
States with maximum interstate highway speed 7
37 treat some type of pain.Approximately of all
limits up to and including 70 mph was . The 50
50
17 aspirin use is for treating headaches.What fraction of
fraction of states with 70 mph speed limits was .
50 aspirin use is for treating pain other than headaches?
What fraction of states had speed limits that were (Source: Bayer Market Research)
less than 70 mph? (Source: Insurance Institute for
Highway Safety)

The map of the world below shows the fraction of the world’s surface land area taken up by each continent. In other
20
words, the continent of Africa makes up of the land in the world. Use this map to solve Exercises 51 through 54.
100
Write answers in simplest form.
Arctic Ocean

7
30
North 100 Europe Asia
America 100
Atlantic
16 Pacific
100 Ocean Africa Ocean
Pacific
Ocean South 20 Indian
America 100 Ocean
Australia
12
100
6
9 100
100
Antarctica

51. Find the fractional part of the world’s land area 52. Find the fractional part of the world’s land area within
within the continents of North America and South the continents of Asia and Africa.
America.