3 . The number of food delivery cars and the number of people using food delivery cars in a town is studied .
The number of food delivery cars in the town after t weeks is modeled by the function At ( ) �1050 � 1.25 t .
2
( a ) Find the initial number of food delivery cars . [ 2 ]
( b ) Find the number of food delivery cars after sixteen weeks . [ 2 ]
( c ) How long does it take for the number of food delivery cars to reach 4200 ? [ 4 ]
The number of people using food delivery cars in the town after t weeks is modeled by 410000 the function Bt () � .
75k�
95 kt
e �
( d ) After twelve weeks , there are 4600 people using food delivery cars . Find the value of k .
[ 3 ] ( e ) The number of food delivery cars first exceeds double the number of people using food delivery cars after n weeks , where n� . Find the value of n . [ 4 ]
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) 4
0.12t
� e .
( a ) Find the air pressure in machine A after half an hour .
( b ) 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 values of kt
[ 2 ]
[ 3 ] . It
( i ) Q
0
;
( ii ) k . [ 5 ]
( d ) The sum of air pressures in two machines first exceeds 400 units after n minutes , where n� . Find the value of n .
[ 4 ] www . seprodstore . com
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