questions 3-8
on each day of the monday through friday workweek，
exactly two of three employees-george， hilda， and
irene-must remain on duty in the office to answer tele-
phones during the noon to 1 p.m. lunch break. in the
scheduling of telephone duty the following constraints
must be met：
hilda and irene have telephone duty together on
tuesday.
george and hilda have telephone duty together on
thursday.
no one can have telephone duty on more than four of the
five days of the week.
3.which of the following can be the week's telephone
duty schedule？
monday tuesday wednesday thursday friday
（a） george george hilda george hilda
hilda irene irene hilda irene
（b） george hilda george hilda george
hilda irene hilda irene irene
（c） george hilda george george george
irene irene hilda hilda hilda
（d） hilda hilda george george hilda
irene irene hilda hilda irene
（e） hilda hilda george george george
irene irene hilda irene irene
4.if hilda has telephone duty for exactly two days of
the week， which of the following must be true？
（a）george and irene have telephone duty together
on wednesday.
（b）george and hilda have telephone duty together
on friday.
（c）hilda and irene have telephone duty together on
wednesday.
（d）hilda and irene have telephone duty together on
friday.
（e）irene has telephone duty for exactly three days
of the week.
5.if hilda and irene have telephone duty together on
monday and on wednesday， which of the following
must be true？
（a）george and hilda have telephone duty together
on friday.
（b）george and irene have telephone duty together
on friday.
（c）george has telephone duty on exactly three of
the days of the week.
（d）hilda has telephone duty on exactly three of the
days of the week.
（e）irene has telephone duty on exactly three of the
days of the week.
6.if george and hilda have telephone duty together on
monday and george and irene have telephone duty
together on friday， any of the following can be true
except：
（a）george and hilda have telephone duty together
on wednesday.
（b）george and irene have telephone duty together
on wednesday.
（c）george has telephone duty for four days of the
week.
（d）irene has telephone duty for four days of the
week.
（e）hilda and irene have telephone duty together for
two days of the week.
7.if there is one pair of employees who have telephone
duty together for three of the five days， which of the
following must be true？
（a）george has telephone duty on wednesday.
（b）george and hilda have telephone duty together
for three days of the week.
（c）hilda and irene have telephone duty together for
three days of the week.
（d）one of the three employees has telephone duty
for exactly two days of the week.
（e）exactly one of the workers has telephone duty
for exactly three days of the week.
8.any of the following can be true except：
（a）one pair of employees has telephone duty
together for exactly one day of the week
（b）one pair of employees has telephone duty
together for exactly four days of the week
（c）the pair of employees that has telephone duty
together on monday also has telephone duty
together on wednesday
（d）the pair of employees that has telephone duty
together on tuesday also has telephone duty
together on wednesday
（e）the pair of employees that has telephone duty
together on thursday also has telephone duty
together on friday