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Date May 2018 Marks available 2 Reference code 18M.2.SL.TZ0.4
Level SL Paper 2 Time zone no time zone
Command term Calculate Question number 4 Adapted from N/A

Question

Ralph owns a furniture store that trades in second-hand furniture, lamps and musical instruments. He buys these items, repairs them where necessary and then resells them.

He calculates the value of each item using the information below:

Ralph is going to use a spreadsheet to model this information.

The spreadsheet model will inform Ralph as to whether he should buy an item. The decision to buy is based on the following rules:

Ralph will not buy any item with a value calculated to be over $90.

The model is also used to calculate his final selling price for each item. This price is calculated using the following rules:

Copy and complete the following table showing the variables, each variable’s data type and range of values that would represent the information shown above.

[4]
a.

Using the above rules, construct the pseudocode that will help Ralph in deciding whether to buy an item.

[4]
b.i.

Describe two items that would have a calculated value of more than $90.

[2]
b.ii.

Calculate the selling price of a top brand guitar with a volume of 96 dm3 that was damaged. You should show your working.

[2]
c.

With the help of a diagram, suggest an appropriate design for a spreadsheet used to calculate the final selling price, following this model.

[4]
d.

Identify two tests that should be included in the test plan for this model.

[2]
e.

Markscheme

Award [4 max]:
Award [1] for each fully correct row indicating variable name, type, and values (no marks for incomplete information, but do allow abbreviated strings)

e.g.

Note: If a full column is missing, then award [1] for each correct column (for a max of [2]).

a.

Award [4 max]:
Award [1]: correct initialisation of Initvalue.
Award [1]: correct calculation of Temp.
Award [1]: correct comparison of Temp with 90.
Award [1]: correct return/output.

proc Decide(Item, Vol)
Var Temp
if Item = f then Initvalue = 100
else if Item = l then Initvalue = 30
else if Item = m then Initvalue = 80;
endif
if Vol >= 500 then Temp = 0.7 * Initvalue // accept <,>
else if Vol =< 30 then Temp = 1.2 * Initvalue
else Temp = Initvalue;
endif
if Temp > 90 then
return "Reject" // accept any 2 reasonable outputs
else return "Accept";
endif
b.i.

Any item of furniture with a volume < 500 dm3;
Any musical instrument with a volume 30 dm3;

Example answers:
A piece of furniture with volume of 400 dm3;
A piece of furniture with volume < 30 dm3;
A flute with volume of 1 dm3;

b.ii.

Award [2 max]:
Award [2] for completely correct answer (only the left or right-hand side needs to be shown).
Award [1] for correctly writing just 4 factors from the left-hand side.

5 * 80 * 3 * 3 * (80/100) = $2880

Alternative expression for the left-hand side:

5 * (Item.IType.Initvalue) * (Item.IType.IBrand) *
(Item.IVol.Percentage) * (Item.ICond.Multiplier)

c.

Award up to [4 max].
Award [1] for some layout design.
Award [1] for each of the following elements:

Example for [2]:
Award [1] for the general layout.
Award [1] for detail (Vlookup table, explanations).

d.

Award [3 max]:
Type consistency, e.g. currency, integer, floating
Range consistency, depending on the decision procedure,
Value at the limits given by the specification (e.g. < or =<)

Accept any testing that relates to

Note: Answers must be more specific than alpha/beta testing, dry-run, etc.

e.

Examiners report

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

Syllabus sections

Option B: Modelling and simulation » B.2 Simulations
Show 44 related questions
Topic 4: Computational thinking, problem-solving and programming » 4.2 Connecting computational thinking and program design
Topic 4: Computational thinking, problem-solving and programming
Option B: Modelling and simulation

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