Counting Handout 1
compiled by Joe Kahlig, Spring 2005
The majority of these problems are from
Finite Mathematics, An
applied approach
, by Paul Long and Jay Graening.
Video solutions located at:
http://www.math.tamu.edu/
∼
kahlig/141extrainfo.html
In the following exercise, use any appropriate technique that has
been presented to obtain the count requested.
1.
Social Security Number
How many different Social Secu
rity numbers are there if
(a) There are no restrictions?
(b) No number can begin with zero?
(c) Neither of the first two digits can be zero?
2.
Telephone Numbers
How many different sevendigit tele
phone numbers can be put on the 501 area code if
(a) There are no restrictions?
(b) No telephone number can begin with zero?
(c) No telephone number can begin with zero and the last
digit must be odd?
3.
Arrangements
In how many ways can five boys and three
girls be seated in a row if
(a) There are no restrictions?
(b) Boys and girls are seated alternately?
(c) A girl must be seated in both end seats?
4.
Arrangements
In how many ways can five boys and five
girls be seated in a row if
(a) Boys and girls are seated alternately?
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 Fall '08
 JillZarestky
 Counting, Sue, ﬁrst digit

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