An environmental study models the concentration of a pollutant, PPP, in a stream as P=ln(0.8t)P = \ln(0.8t)P=ln(0.8t), where t>0t > 0t>0 is the time in hours after a treatment process begins. Determine the exact value of the rate of change of the concentration with respect to time at the instant when t=2.5t = 2.5t=2.5.
263 exam-style questions on CCEA A Level Maths 3.5 Differentiation (A-level only), covering 3.5.1 Differentiation (A-level only), 3.5.2 Differentiation (A-level only), 3.5.3 Differentiation (A-level only), 3.5.4 Differentiation (A-level only), 3.5.5 Differentiation (A-level only), and 3.5 Differentiation (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.