(ii) If the largest absolute deviations for the Chebyshev's criterion and that of the Least
Squares criterion are given respectively by Cmax and dmax, define them and then compute
their values including their least bound D to express their relationship for the above data
and the model line.
[10)
QUESTION 4 [30 MARKS]
(a) Suppose a certain drug is effective in treating a disease if the concentration remains
above 120 mg/L. The initial concentration is 645 mg/L. It is known from laboratory
experiments that the drug decays at the rate of 25% of the amount present each hour.
(i) Formulate a model representing the concentration at each hour.
[2]
(ii) Build a table of values (answer correct to 2 decimal places) and determine when the
concentration reaches 120 mg/L.
[12)
(b) Consider the following table showing the experimental data of the growth of a
micro-organism.
n0
Yn 8.2
!J.yn 8.7
1
2
15.3 29.2
11.7 16.3
3
45.5
23.9
4
71.1
52
5
120.1
55.5
6
174.6
85.6
where n is the time in days and Yn is the observed organism biomass.
(i) Construct a linear model for the above organism growth and show that the model
predicts an increasing population without limit.
(ii) Assume that contrary to your model prediction in (i), there is a maximum population
of 665. Hence formulate a nonlinear dynamical system model for the organism using
your constant obtained from an appropriate ratio similar to the example given in class,
= for n 3 in the above data.
[16)
END OF QUESTIONPAPER
TOTAL MARKS= 120
3 I 1)u g l'