AQA Further Paper 2 2022 June — Question 14 5 marks

Exam BoardAQA
ModuleFurther Paper 2 (Further Paper 2)
Year2022
SessionJune
Marks5
TopicSecond order differential equations

14 On an isolated island some rabbits have been accidently introduced. In order to eliminate them, conservationists have introduced some birds of prey.
At time \(t\) years \(( t \geq 0 )\) there are \(x\) rabbits and \(y\) birds of prey.
At time \(t = 0\) there are 1755 rabbits and 30 birds of prey.
When \(t > 0\) it is assumed that:
  • the rabbits will reproduce at a rate of \(a \%\) per year
  • each bird of prey will kill, on average, \(b\) rabbits per year
  • the death rate of the birds of prey is \(c\) birds per year
  • the number of birds of prey will increase at a rate of \(d \%\) of the rabbit population per year.
This system is represented by the coupled differential equations: $$\begin{aligned} & \frac { \mathrm { d } x } { \mathrm {~d} t } = 0.4 x - 13 y
& \frac { \mathrm {~d} y } { \mathrm {~d} t } = 0.01 x - 1.95 \end{aligned}$$ 14
  1. State the value of \(a\), the value of \(b\), the value of \(c\) and the value of \(d\)
    [0pt] [2 marks]
    14
  2. Solve the coupled differential equations to find both \(x\) and \(y\) in terms of \(t\)