105.The recommended daily intake (RDI) of calcium for females aged 19 – 50 is 1000 mg.
Actual needs vary from person to person. Write this statement as an absolute value in-
equality, with xrepresenting the RDI, to express the RDI plus or minus 100 mg, and
solve the inequality. (Source:National Academy of Sciences — Institute of Medicine.)
106.The average clotting time of blood is 7.45 sec, with a variation of plus or minus 3.6 sec.
Write this statement as an absolute value inequality, with xrepresenting the time, and
solve the inequality.
120 CHAPTER 2 Linear Equations, Inequalities, and Applications
EXERCISES 107–110
FOR INDIVIDUAL OR GROUP WORK
The 10 tallest buildings in Houston, Texas, as of 2009 are listed, along with their
heights.
RELATING CONCEPTS
Source: World Almanac and Book of Facts.
Use this information to work Exercises 107 – 110 in order.
107.To find the average of a group of numbers, we add the numbers and then divide by
the number of numbers added. Use a calculator to find the average of the heights.
108.Let krepresent the average height of these buildings. If a height xsatisfies the
inequality
,
then the height is said to be within tfeet of the average. Using your result from
Exercise 107,list the buildings that are within 50 ft of the average.
109.Repeat Exercise 108,but list the buildings that are within 95 ft of the average.
- (a)Write an absolute value inequality that describes the height of a building that
is notwithin 95 ft of the average.
(b)Solve the inequality you wrote in part (a).
(c)Use the result of part (b) to list the buildings that are not within 95 ft of the
average.
(d)Confirm that your answer to part (c) makes sense by comparing it with your
answer to Exercise 109.
|x-k| 6 t
For the equations (a) and (b) find y for the given value
of x. See Section 1.3.
111.x= 0 112.x=- 2 113.x= 8 114.x= 1.5
3 x+ 2 y=24, - 2 x+ 5 y=20,
PREVIEW EXERCISES
Height
Building (in feet)
JPMorgan Chase Tower 1002
Wells Fargo Plaza 992
Williams Tower 901
Bank of America Center 780
Texaco Heritage Plaza 762
Enterprise Plaza 756
Centerpoint Energy Plaza 741
Continental Center I 732
Fulbright Tower 725
One Shell Plaza 714
