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Exponentials and Logarithms

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Question 148

The temperature of water in a kettle is modelled using the equation T=75e−kt+25T = 75e^{-kt} + 25T=75e−kt+25

a.

Explain what the 25 represents in the equation T=75e−kt+25T = 75e^{-kt} + 25T=75e−kt+25

[1]
b.

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

[3]
c.

Find how many minutes it takes for the water to cool to 55∘C55^{\circ}\text{C}55∘C

[3]
Markscheme

Exponentials and Logarithms Questions

  1. A Level
  2. /Maths
  3. /Exponentials and Logarithms

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.

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