SPS SPS SM Pure 2025 February — Question 5

Exam BoardSPS
ModuleSPS SM Pure (SPS SM Pure)
Year2025
SessionFebruary
TopicExponential Equations & Modelling

5. The number of bacteria on a surface is being monitored. The number of bacteria, \(N\), on the surface, \(t\) hours after monitoring began is modelled by the equation $$\log _ { 10 } N = 0.35 t + 2$$ Use the equation of the model to answer parts (a) to (c).
  1. Find the initial number of bacteria on the surface.
  2. Show that the equation of the model can be written in the form $$N = a b ^ { t }$$ where \(a\) and \(b\) are constants to be found. Give the value of \(b\) to 2 decimal places.
  3. Hence find the rate of growth of bacteria on the surface exactly 5 hours after monitoring began.