The temperature of water in a kettle is modelled using the equation T=75e−kt+25T = 75e^{-kt} + 25T=75e−kt+25
Explain what the 25 represents in the equation T=75e−kt+25T = 75e^{-kt} + 25T=75e−kt+25
When the kettle is turned off the rate of decrease of the water temperature is 20∘C20^{\circ}\text{C}20∘C per minute. Find the value of kkk
Find how many minutes it takes for the water to cool to 55∘C55^{\circ}\text{C}55∘C
Practise AQA A Level Maths 1.9 F: Exponentials and logarithms with exam-style questions for A Level Maths. 37 questions covering 1.9.1 Exponential functions and their graphs, 1.9.2 Gradient of e^kx (A-level only), 1.9.3 Logarithms as inverse functions, 1.9.4 Laws of logarithms, 1.9.5 Solving exponential equations, 1.9.6 Logarithmic graphs to estimate parameters (A-level only), and 1.9.7 Exponential growth and decay, matched to the AQA A Level Maths (7357) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
