(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
- (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.
- 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
- for r
(circumference of a circle)
C= 2 pr 8. for h
(area of a triangle)
a=
1
2
bh
r h
b