Page 494 - Basic College Mathematics with Early Integers

S E C T I O N 6.4 I APPLICATIONS OF PERCENT 471

Next, we solve for n.

#
31 = 0.04 n Write 4% as a decimal.
31
= n Divide 31 by 0.04, the number multiplied by n.
0.04
775 = n Simplify.

There are 775 freshmen at Slidell High School.
Method 2. First we state the problem in words; then we translate.
In words: 31 is 4% of what number ?
('')''*
T T
Î
amount percent base
Translate: amount : 31 4 ; percent
=
base : b 100
Next, we solve for b.

#
#
31 100 = b 4 Set cross products equal.
#
3100 = b 4 Multiply.
3100
= b Divide 3100 by 4, the number multiplied by b.
4
775 = b Simplify.
There are 775 freshmen at Slidell High School.

Work Practice 3

Example 4 Finding the Base Increase in Licensed Drivers PRACTICE 4
From 2000 to 2007, the number
From 2000 to 2007, the number of licensed drivers on the road in the United States of registered vehicles on the
increased by 6.5%. In 2000, there were 190 million licensed drivers on the road.
road in the United States
a. Find the increase in licensed drivers from 2000 to 2007. increased by 3%. In 2000, the
b. Find the number of licensed drivers on the road in 2007. number of vehicles on the road
was 240 million.
(Source: Federal Highway Administration)
a. Find the increase in the
number of vehicles on the
road in 2007.
b. Find the total number of
registered vehicles on the
road in 2007.
(Source: Federal Highway
Administration)

Solution: Method 1. First we find the increase in licensed drivers.

In words: What number is 6.5% of 190?
('')''*
T T T T T Answers
Translate: n = 6.5% # 190 Continued on next page 4. a. 7.2 million b. 247.2 million