Page 496 - Basic College Mathematics with Early Integers

S E C T I O N 6.4 I APPLICATIONS OF PERCENT 473

Example 5 Finding Percent Increase PRACTICE 5
The number of people attending
The number of applications for a mathematics scholarship at Yale increased from the local play,Peter Pan,
34 to 45 in one year. What is the percent increase? Round to the nearest whole increased from 285 on Friday to
percent.
333 on Saturday.Find the percent
Solution: First we find the amount of increase by subtracting the original increase in attendance.Round to
number of applicants from the new number of applicants. the nearest tenth percent.
amount of increase = 45 - 34 = 11
The amount of increase is 11 applicants.To find the percent of increase,
Make sure that
amount of increase 11
percent of increase = = L 0.32 = 32% this number is the original
original amount 34
number and not the new
The number of applications increased by about 32%. number.

Work Practice 5

Concept Check A student is calculating the percent increase in enrollment
from 180 students one year to 200 students the next year. Explain what is wrong
with the following calculations:

Amount
= 200 - 180 = 20
of increase
Percent of 20
= = 0.1 = 10%
increase 200
Suppose that your income was $300 a week and then it decreased by $30. The
percent of decrease is
amount of decrease : $30
= 0.1 = 10%
original amount : $300

Percent of Decrease

amount of decrease
percent of decrease =
original amount
Then write the quotient as a percent.

Example 6 Finding Percent Decrease PRACTICE 6
A town with a population of
In response to a decrease in sales, a company with 1500 employees reduces the
20,200 in 1995 decreased to
number of employees to 1230.What is the percent decrease?
18,483 in 2005.What was the
Solution: First we find the amount of decrease by subtracting 1230 from 1500. percent decrease?
amount of decrease = 1500 - 1230 = 270
The amount of decrease is 270 .To find the percent of decrease,
percent of amount of decrease 270
= = = 0.18 = 18%
decrease original amount 1500
The number of employees decreased by 18%. Answers
5. 16.8% 6. 8.5%
Work Practice 6
Concept Check Answers
Concept Check An ice cream stand sold 6000 ice cream cones last summer. To find the percent of increase, you
This year the same stand sold 5400 cones. Was there a 10% increase, a 10% have to divide the amount of increase
(20) by the original amount (180);
decrease, or neither? Explain. 10% decrease.