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Date May 2022 Marks available 2 Reference code 22M.2.SL.TZ2.4
Level Standard Level Paper Paper 2 Time zone Time zone 2
Command term Calculate Question number 4 Adapted from N/A

Question

The Texas Star is a Ferris wheel at the state fair in Dallas. The Ferris wheel has a diameter of 61.8m. To begin the ride, a passenger gets into a chair at the lowest point on the wheel, which is 2.7m above the ground, as shown in the following diagram. A ride consists of multiple revolutions, and the Ferris wheel makes 1.5 revolutions per minute.

The height of a chair above the ground, h, measured in metres, during a ride on the Ferris wheel can be modelled by the function h(t)=acos(bt)+d, where t is the time, in seconds, since a passenger began their ride.

Calculate the value of

A ride on the Ferris wheel lasts for 12 minutes in total.

For exactly one ride on the Ferris wheel, suggest

Big Tex is a 16.7 metre-tall cowboy statue that stands on the horizontal ground next to the Ferris wheel.


[Source: Aline Escobar., n.d. Cowboy. [image online] Available at: https://thenounproject.com/search/?q=cowboy&i=1080130
This file is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)
https://creativecommons.org/licenses/by-sa/3.0/deed.en [Accessed 13/05/2021]. Source adapted.]

There is a plan to relocate the Texas Star Ferris wheel onto a taller platform which will increase the maximum height of the Ferris wheel to 65.2m. This will change the value of one parameter, a, b or d, found in part (a).

a.

[2]
a.i.

b.

[2]
a.ii.

d.

[2]
a.iii.

Calculate the number of revolutions of the Ferris wheel per ride.

[2]
b.

an appropriate domain for h(t).

[1]
c.i.

an appropriate range for h(t).

[2]
c.ii.

By considering the graph of h(t), determine the length of time during one revolution of the Ferris wheel for which the chair is higher than the cowboy statue.

[3]
d.

Identify which parameter will change.

[1]
e.i.

Find the new value of the parameter identified in part (e)(i).

[2]
e.ii.

Markscheme

an attempt to find the amplitude          (M1)

61.82   OR   64.5-2.72

a=  30.9m          A1


Note: Accept an answer of a=  -30.9m.

 

[2 marks]

a.i.

(period =601.5=)  40s          (A1)

(b= 360°40)

b= 9          A1


Note: Accept an answer of b= -9.

 

[2 marks]

a.ii.

attempt to find d          (M1)

d= 30.9+2.7   OR   64.5+2.72

d=  33.6m          A1

 

[2 marks]

a.iii.

12×1.5   OR   12×6040          (M1)

18 (revolutions per ride)          A1

 

[2 marks]

b.

0t720         A1

 

[1 mark]

c.i.

2.7h64.5         A1A1

 

Note: Award A1 for correct endpoints of domain and A1 for correct endpoints of range. Award A1 for correct direction of both inequalities.

 

[2 marks]

c.ii.

graph of h(t) and y=16.7   OR   h(t)=16.7           (M1)

6.31596   and   33.6840           (A1)

27.4s   27.3680         A1

 

[3 marks]

d.

d       A1

 

[1 mark]

e.i.

EITHER

d+30.9=65.2            (A1)


OR

65.2-61.8+2.7=0.7            (A1)


OR

3.4  (new platform height)            (A1)


THEN

d= 34.3m         A1

 

[2 marks]

e.ii.

Examiners report

Overall, this question was not well answered. Part (a) proved to be problematic for most candidates – hardly any candidates determined all three parameters correctly. The value of b was rarely found. Most candidates were able to find the number of revolutions in part (b). Only a small number of candidates were able to determine the domain and range in part (c) correctly. In part (d), a number of candidates understood that they needed to solve the equation h(t)=1.67, and gained the method mark, but very few candidates gained all three marks. In part (e), determining the parameter which would change proved challenging, and few were able to determine correctly how the parameter d would change.

a.i.
[N/A]
a.ii.
[N/A]
a.iii.
[N/A]
b.
[N/A]
c.i.
[N/A]
c.ii.
[N/A]
d.
[N/A]
e.i.
[N/A]
e.ii.

Syllabus sections

Topic 2—Functions » SL 2.5—Modelling functions
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