College Algebra & Trigonometry, 2018a

7.4. GENERAL COMBINATORICS PROBLEMS 323
17) In how many ways can four men and four women be seated in a row of
eight seats if:
SET III
a) The first seat is occupied by a man
b) The first and last seats are occupied by women
18) The social security number of a person is a sequence of nine digits that are
not necessarily distinct. How many social security numbers are possible?
19) A variable name in the BASIC programming language is either a letter of
the alphabet or a letter followed by a digit. How many distinct variable names
are there in the BASIC language?
20) a) How many even numbers are there between 0 and 100?
100?
b) How many even numbers with distinct digits are there between 0 and
21) There are six characters - three letters of the English alphabet followed by
three digits - which appear on the back panel of a particular brand of printer as
an identification number. Find the number of possible identification numbers if:
a) characters can be repeated
b) digits cannot repeat
c) letters cannot repeat
d) characters cannot repeat