Intermediate Algebra (11th edition)

(Marvins-Underground-K-12) #1

(b)The enrollment at a community college declined from 12,750 during one school


year to 11,350 the following year. Find the percent decrease to the nearest tenth.


Let the percent decrease (as a decimal).


Substitute the given values.

xL0.11,or11% Use a calculator.


x=


1400


12,750


x=


12,750-11,350


12,750


percent decrease=


amount of decrease


base


x=


62 CHAPTER 2 Linear Equations, Inequalities, and Applications


CAUTION When calculating a percent increase or decrease, be sure that you use


the original number (beforethe increase or decrease) as the base. A common error is


to use the final number (afterthe increase or decrease) in the denominator of the


fraction.


NOW TRY
EXERCISE 8

(a)Jane Brand bought a jacket
on sale for $56. The
regular price of the jacket
was $80. What was the
percent markdown?


(b)When it was time for
Horatio Loschak to renew
the lease on his apartment,
the landlord raised his rent
from $650 to $689 a
month. What was the
percent increase?


NOW TRY ANSWERS



  1. (a)30% (b)6%


Subtract to find the
amountof decrease.

Use the original
number.

The college enrollment decreased by about 11%. NOW TRY


Complete solution available
on the Video Resources on DVD


2.2 EXERCISES


Solve each formula for the specified variable. See Examples 1–3.
1.I=prtfor r (simple interest) 2.d=rtfor t (distance)

*In this book, we use ato denote area.


  1. for L
    ( perimeter of a rectangle)


P= 2 L+ 2 W 4.a=bhfor b(area of a parallelogram)*

W

L
h

b
5.
(volume of a rectangular solid)
(a)for W (b)for H

6.


( perimeter of a triangle)
(a)for b (b) for c

b

c

a

P=a+b+c

L

H
W

V=LWH



  1. for r
    (circumference of a circle)


C= 2 pr 8. for h

(area of a triangle)

a=

1


2


bh

r h

b
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