Intermediate Algebra (11th edition)

Finding the Arithmetic Mean, or Average

The following table shows the number of FDIC-insured financial institutions for

each year during the period from 2002 through 2008. What was the average number

of institutions per year for this 7-yr period?

EXAMPLE 6

682 CHAPTER 12 Sequences and Series

Source:U.S. Federal Deposit Insurance Corporation.

Year Number of Institutions 2002 9369 2003 9194 2004 8988 2005 8845 2006 8691 2007 8544 2008 8314

Let and so on. There are 7 numbers in the group, so

(rounded to the nearest unit)

The average number of institutions per year for this 7-yr period was 8849.

NOW TRY

= 8849

=

9369 + 9194 + 8988 + 8845 + 8691 + 8544 + 8314

7

n=7.

x 1 =9369,x 2 =9194,

x=

a

7

i= 1

xi

7

NOW TRY
EXERCISE 6
The following table shows the
top 5 American Quarter Horse
States in 2009 based on the
total number of registered
Quarter Horses. To the nearest
whole number, what is the
average number of Quarter
Horses registered per state in
these top five states?

NOW TRY ANSWER
6.197,521

Source:American Quarter Horse
Association.

Number of Registered State Quarter Horses Texas 461,054 Oklahoma 188,381 California 136,583 Missouri 107,630 Colorado 93,958

Complete solution available
on the Video Resources on DVD

Write out the first five terms of each sequence. See Example 1.

4. 5. 6.

7. 8. 9.

10. 11. 12.

Find the indicated term for each sequence. See Example 1.

; 14. ;

; 16. ;

17.an= 1 n+ 1212 n+ 32 ; a 8 18.an= 15 n- 2213 n+ 12 ; a 10

an= a 16

5 n- 9 3 n+ 8

an= a 14

3 n+ 7 2 n- 5

an=- 9 n+ 2 a 8 an= 3 n- 7 a 12

an=n+

4

n

an=n-

1

n

an= 61 - 12 n+^1

an= an= 51 - 12 n-^1

- 2

n 2

an=

1

n 2

an= an= 3 n an= 2 n

n+ 2 n

an=

n+ 3 n

an=n+ 1 an=n+ 4

12.1 EXERCISES