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1.6 Exponentials and logarithms

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Question 33

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]

1.6 Exponentials and logarithms Questions

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