FDPR Mixed Context: WJEC GCSE Numeracy Intermediate June 2018 Unit 2 Q2

Numeracy Intermediate June 2018 Unit 2 Q2

WJECIntermediateCurrent spec9 marksFDPR Mixed Context Units & Time

2. Miss Price has received her total bill for water.
It is based on estimates of how much fresh water is used and how much waste water is produced.
Her bill is £58.80.

Miss Price’s actual use of water was as follows:

fresh water used 25·25 m³,
waste water produced 22·31 m³.

Fresh water used costs £1.08 per m³.
Waste water produced costs £1.70 per m³.

(a)

In this part of the question, you will be assessed on the quality of your organisation, communication and accuracy in writing.

By how much has Miss Price been overcharged or undercharged?
You must show all your working. [4 + 2 OCW]

(b)

(i)

Remember
1 m³ ≈ 220 gallons

Use this conversion to calculate how much fresh water Miss Price used in gallons. [2]

…………… gallons

(ii)

Explain why your answer in part (b)(i) is not the exact number of gallons Miss Price used. [1]

Mark scheme (a)

Scheme	Marks	Comments
(Fresh water charge £) 25.25 × 1.08 (= 27.27)	M1
(Waste water charge £) 22.31 × 1.70 (=37.927)	M1
(Total bill £27.27 + £37.927 = £) 65.19(7) or 65.2(0)	A1	CAO
Undercharged (by) (£)6.4(0) or (£)6.39(7)	B1	Must state under charged and the amount, however accept –(£)6.4(0) or –(£)6.39(7) FT difference between ‘their derived total’ and £58.80 with appropriate conclusion, over or under charged
Organisation and communication	OC1	For OC1, candidates will be expected to: present their response in a structured way explain to the reader what they are doing at each step of their response lay out their explanations and working in a way that is clear and logical write a conclusion that draws together their results and explains what their answer means
Writing	W1	For W1, candidates will be expected to: show all their working make few, if any, errors in spelling, punctuation and grammar use correct mathematical form in their working use appropriate terminology, units, etc.

Mark scheme (b)

Scheme	Marks	Comments
(i) 25.25 × 220	M1
5555 (gallons)	A1	Mark final answer If no marks SC1 for either (47.56 × 220 =) 10463(.2 gallons), or (22.31 × 220 =) 4908(.2 gallons)
(ii) Suitable reason, e.g. ‘as the conversion was only approximate’, ‘the gallons could have been rounded up or down’, ‘because it is to the nearest gallon’	E1	Accept ‘I rounded my answer’ following (b)(i) having been rounded, otherwise do not accept, e.g. ‘Miss Price’s bill may have been rounded up or down’ Do not accept, e.g. ‘she could have used less or more’, ‘she did not use an exact number of gallons’ (as this repeats the question), ‘she rounded up the amount of fresh water used’, ‘it is based on an estimate of how much fresh water is used and how much waste water is produced’, ‘it is likely she used just over or under a certain number of gallons’, ‘because it is an estimate’