Edexcel P3 2020 January — Question 1

Exam BoardEdexcel
ModuleP3 (Pure Mathematics 3)
Year2020
SessionJanuary
TopicExponential Functions

  1. A population of a rare species of toad is being studied.
The number of toads, \(N\), in the population, \(t\) years after the start of the study, is modelled by the equation $$N = \frac { 900 \mathrm { e } ^ { 0.12 t } } { 2 \mathrm { e } ^ { 0.12 t } + 1 } \quad t \geqslant 0 , t \in \mathbb { R }$$ According to this model,
  1. calculate the number of toads in the population at the start of the study,
  2. find the value of \(t\) when there are 420 toads in the population, giving your answer to 2 decimal places.
  3. Explain why, according to this model, the number of toads in the population can never reach 500