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Date May Example question Marks available 3 Reference code EXM.1.AHL.TZ0.15
Level Additional Higher Level Paper Paper 1 Time zone Time zone 0
Command term Hence and Find Question number 15 Adapted from N/A

Question

Adesh wants to model the cooling of a metal rod. He heats the rod and records its temperature as it cools.

He believes the temperature can be modeled by  T ( t ) = a e b t + 25 , where a , b R .

Hence

Show that  ln ( T 25 ) = b t + ln a .

[2]
a.

Find the equation of the regression line of  ln ( T 25 ) on  t .

[3]
b.

find the value of a  and of b .

[3]
c.i.

predict the temperature of the metal rod after 3 minutes.

[2]
c.ii.

Markscheme

ln ( T 25 ) = ln ( a e b t )        M1

ln ( T 25 ) = ln a + ln ( e b t )             A1

ln ( T 25 ) = b t + ln a             AG

[2 marks]

a.

ln ( T 25 ) = 0.00870 t + 3.89       M1A1A1

[3 marks]

b.

b = 0.00870        A1

a = e 3.89... = 49.1      M1A1

[3 marks]

c.i.

T ( 180 ) = 49.1 e 0.00870 ( 180 ) + 25 = 35.2     M1A1

[2 marks]

c.ii.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.i.
[N/A]
c.ii.

Syllabus sections

Topic 4—Statistics and probability » SL 4.4—Pearsons, scatter diagrams, eqn of y on x
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Topic 2—Functions » AHL 2.10—Scaling large numbers, log-log graphs
Topic 2—Functions
Topic 4—Statistics and probability

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