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Date May 2017 Marks available 2 Reference code 17M.2.SL.TZ2.S_4
Level Standard Level Paper Paper 2 Time zone Time zone 2
Command term Find Question number S_4 Adapted from N/A

Question

The depth of water in a port is modelled by the function d ( t ) = p cos q t + 7.5 , for 0 t 12 , where t is the number of hours after high tide.

At high tide, the depth is 9.7 metres.

At low tide, which is 7 hours later, the depth is 5.3 metres.

Find the value of p .

[2]
a.

Find the value of q .

[2]
b.

Use the model to find the depth of the water 10 hours after high tide.

[2]
c.

Markscheme

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

valid approach     (M1)

eg max min 2 , sketch of graph, 9.7 = p cos ( 0 ) + 7.5

p = 2.2     A1     N2

[2 marks]

a.

valid approach     (M1)

eg B = 2 π period , period is 14 ,   360 14 ,   5.3 = 2.2 cos 7 q + 7.5

0.448798

q = 2 π 14   ( π 7 ) , (do not accept degrees)     A1     N2

[2 marks]

b.

valid approach     (M1)

eg d ( 10 ) ,   2.2 cos ( 20 π 14 ) + 7.5

7.01045

7.01 (m)     A1     N2

[2 marks]

c.

Examiners report

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

Syllabus sections

Topic 2—Functions » SL 2.5—Modelling functions
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