110 Unit 3 Problem solving: basic skills
at half the time shown in the graphs,
patients have stopped taking it.
Assuming that the effects of the
two drugs are independent, what would
be the expected shape of the graph of
effectiveness for a patient on the regime
described?
2 At a local school, 70% of the students
studied French and 45% studied German.
Which of the following can be confirmed
from the information given?A All students study either French or
German.
B 23 of those studying German do not
study French.
C 25% of the students study neither
French nor German.
D At least 15% of students study both
French and German.
3 I was shopping at a market in Northern
Bolandia and asked a local how much an
orange was. He said that an orange and a
lemon together cost $2. He then further
confused me by saying that a grapefruit
and a lemon cost $3 and that all three
were different prices.
Based on this rather unhelpful
information, which one of the following can
be confirmed?A An orange costs more than a lemon.
B A lemon costs more than a
grapefruit.
C A grapefruit costs more than a
dollar.
D An orange costs less than a dollar.1 In order to treat a particular disease
effectively, patients are initially given two
drugs. Drug A alone has the effect shown
on the graph below. (10 = total relief from
symptoms. 1 = no relief.)110TimeAverage e ectivenessDrug AThe effect of drug B showing how it varies
with time is shown in the graph below (on
the same effectiveness and time scales).Average e ectiveness
110TimeDrug BThe reason the patients are given two
drugs is that drug A, whilst being very
effective, has long-term harmful side
effects. Drug B takes some time to
become effective, and has a lower eventual
effect but can be taken indefinitely. The
regime used by doctors is to give both
drugs starting at the same time, then to
withdraw A at a uniform steady rate until,End-of-chapter assignments