Analysis and Approaches for IBDP Maths Ebook 1 | Page 56

Your Practice Set – Analysis and Approaches for IBDP Mathematics
4. The air pressure in two machines, A and B , are recorded in an experiment.
The air pressure in machine A after t minutes is modeled by the function
P( t) 4e
0.12t
� .
(a)
(b)
Find the air pressure in machine A after half an hour.
How long does it take for the air pressure in machine A to reach
8 units?
The air pressure in machine B after t minutes is modeled by the function Q()
t � Q0e
is recorded that the initial air pressure and the air pressure in machine B after half an
hour are 3.5 units and 171 units respectively.
(c) Find the value of Q
0
and of k .
[3]
(d) The sum of air pressures in two machines first exceeds 400 units after n minutes,
where n� . Find the value of n .
[4]
kt
[2]
[3]
. It
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