The temperature of water in a kettle is modelled using the formula T=75e−kt+22T = 75e^{-kt} + 22T=75e−kt+22
Where T T\,T is the temperature t t\,t minutes after the kettle is turned off and k k\,k is a positive constant.
Find the rate of change of the temperature in terms of kkk
The value of k k\,k is 15ln(53)\displaystyle \frac{1}{5}\ln\left(\frac{5}{3}\right)51ln(35). Find the temperature of the water after 5 minutes
Find how many minutes it takes for the water to cool to 49∘C49^\circ\text{C}49∘C
277 exam-style questions on Edexcel A Level Maths Exponentials and Logarithms, covering 14.1 Exponential Functions, 14.2 y = e^x, 14.3 Exponential Modelling, 14.4 Logarithms, 14.5 Laws of Logarithms, 14.6 Solving Equations using Logarithms, 14.7 Working with Natural Logarithms, and 14.8 Logarithms and Non-Linear Data. Each one has a worked solution and a mark scheme showing where the marks go.