UNIT 4 Mathematical Methods, 2019 Modelling / Problem solving task (SAC 2)
Question 1: (35 marks)- DESIGNING & CONSTRUCTING THE SWIMMING POOL
Highvale Secondary College is proposing to build an aquatic centre with a la
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UNIT 4 Mathematical Methods, 2019 Modelling / Problem solving task (SAC 2)
Question 1: (35 marks)- DESIGNING & CONSTRUCTING THE SWIMMING POOL
Highvale Secondary College is proposing to build an aquatic centre with a large swimming pool.
In order to build the pool, the builders must excavate (dig into the ground) to remove the soil. For
this entire SAC, lets assume that the ground is level, and can be shown by the positive x-axis. The
architect in charge of this project has proposed two possible excavation models for the pool.
These are shown below:
3 6 2
: 0,50 where ( ) 2
6250 125
x x
p R p x → = - -
3 2
:[0,50] where ( ) 2
25
x
j R j x → = - -
a. Analyse both functions to determine the following: (write solutions in the table below)
i.
ii.
iii.
iv. | function minimum
function maximum
function range
point(s) of intersection (approximate to 1 decimal place) | 1x4 marks= 4 marks
function minimum
function maximum
function range
point(s) of intersectionb. Sketch the derivative graphs p x j x '( ) and '( ) for both the functions in the given graphing
grid and label all key points ( two decimal places, where approximation is required)
3 marks
UNIT 4 Mathematical Methods, 2019 Modelling / Problem solving task (SAC 2)
Page 2
c. Using Calculus obtain the derivatives p x '( ) and j x '( ) for the functions p x j x ( ) and ( )
2x2 marks= 4marks
d. What information do the two intersection points of the functions p x '( ) and j x '( ) tell us?
2 marks
e. i. Using calculus find the area as an exact value between the function p x x ( ) and the -axis
2 marks
ii. Using calculus find the area as an exact value between the function j x x ( ) and the -axis
2 marks
UNIT 4 Mathematical Methods, 2019 Modelling / Problem solving task (SAC 2)
Page 3
iii. What do you conclude from your answers to parts i. and ii. above? 1 mark
f. i. Find the average value for the function p(x).
ii. What information does this average value convey? | 1 mark
1 mark
i.
ii.g. i. By analyzing all the answers from parts a-e above, which of the two models will you
recommend for excavation? Justify you answer. 2 marks
UNIT 4 Mathematical Methods, 2019 Modelling / Problem solving task (SAC 2)
Page 4
ii. Using Calculus obtain the area bound between the functions p(x) and j(x) given that the
approximate x-coordinate expressed as a fraction for the point of intersection of the two
functions is
. (Answer correct to three decimal places ) | 2 marks19.1 or 191
10
x (After stating the actual Integral / rule with correct limits, you may use a calculator to
approximate values while performing the area calculations)
iii. What conclusion can be drawn about the two individual sectional areas created by the point of
intersection of the functions p(x) and j(x), Use CAS to answer this question? 2 marks
h. Given that the cost of excavation is $ 80 per cubic meter ( m3 ).
The width of the pool, which has to be fitted in the excavated hole, is 25 m.
Determine the total cost for the excavation using the function you chose as your preferred
mode
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