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Differentiation of exponential and logarithmic functions — Question 270

Original QCE Vault practice · 4 marks

Q270 · Practice questionTechnology-freeSimple familiar4 marks

QUESTION 270 (4 marks)

The scent concentration from a diffuser is modelled by

C(t)=Ae^{-kt}

, where

C

is measured in arbitrary units and

t

in hours. Measurements give

C(0)=80

and

C(3)=20

.

Decreasing exponential concentration curve through the labelled points (0,80) and (3,20).

a)

Determine

A

and the exact value of

k

.

[2 marks]

b)

Determine when the concentration first falls to

10

units.

[2 marks]

Question linkSyllabus coverage

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