Page 502 - Basic College Mathematics with Early Integers

S E C T I O N 6.4 I APPLICATIONS OF PERCENT 479

57. In 2006, approximately 504,000 computer systems 58. In 1999, there were 10.9 million total restaurant
analysts were employed in the United States. By 2016, employees in the United States. By 2019, this number
this is expected to increase to 650,000.What is the is expected to increase to 14.8 million.What is the
percent increase? (Source: Bureau of Labor percent increase? (Source: National Restaurant
Statistics) Association)

59. The number of cell phone tower sites in the United 60. The population of Tokyo is expected to decrease from
States was 178,025 in 2005. By 2010, the number of 127,400 thousand in 2005 to 99,900 thousand in 2050.
cell sites had increased to 247,081.What is the percent Find the percent decrease. (Source: International
increase? (Source: CTIA—The Wireless Association) Programs Center, Bureau of the Census, U.S. Dept.
of Commerce)

Japan

Tokyo

Review

Perform each indicated operation. See Sections 4.2 and 4.3.
61. 0.12 62. 42 63. 9.20 + 1.98 64. 46 + 7.89
* 38 * 0.7

65. 78 - 19.46 66. 64.80 - 10.72

Concept Extensions

67. If a number is increased by 100%, how does the 68. In your own words, explain what is wrong with the
increased number compare with the original number? following statement.“Last year we had 80 students
Explain your answer. attend.This year we have a 50% increase or a total
of 160 students attending.”

Explain what errors were made by each student when solving percent of increase or decrease problems and then correct
the errors. See the Concept Checks in this section.

The population of a certain rural town was 150 in 1980, 180 in 1990, and 150 in 2000.
69. Find the percent of increase in population from 1980 to 1990.

30
Miranda’s solution: Percent of increase = = 0.16 L 16.7%
180
70. Find the percent of decrease in population from 1990 to 2000.

30
Jeremy’s solution: Percent of decrease = = 0.20 = 20%
150
71. The percent of increase from 1980 to 1990 is the same as the percent of decrease from 1990 to 2000.True or false.
Chris’s answer:True because they had the same amount of increase as the amount of decrease.