Averages (including IQR): WJEC GCSE Foundation June 2024 Unit 2 Q7

Foundation June 2024 Unit 2 Q7

WJECFoundationCurrent spec4 marksAverages (including IQR)Fractions Using a Calculator / BIDMAS

(a) Jemma is asked to work out the following calculation.

10 + 4 × 9

Jemma’s method is

14 x 9 = 126

Explain why Jemma’s method is wrong. [1]

(b) Sion is asked to answer the following question.

How many halves are there in 20?

Sion’s method is

20 ÷ 2 = 10

Explain why Sion’s method is wrong. [1]

7 1 20 14 11

Rebecca’s method is

11 − 7 = 4

Explain why Rebecca’s method is wrong. [1]

(d) Stef knows what \(\dfrac{1}{5}\) of Paulo’s number is.
Using this information, explain how Stef can work out \(\dfrac{1}{10}\) of Paulo’s number. [1]

Mark scheme (a)

Scheme	Marks	Comments
A correct explanation, e.g. ‘She hasn’t used BIDMAS/ BODMAS/ Order of Operations’. ‘You must multiply before you add’ ‘She should have multiplied first’ ‘She has added the 10 and the 4 first, then multiplied by 9’	E1	Accept ‘10 + 36 = 46’. Award E0 for: an unsupported 46. ‘10 + 4 x 9 = 46’. ‘she added 10 and 4 together’ a correct explanation given but later contradicted a correct explanation given with an incorrect answer to the calculation

Mark scheme (b)

Scheme	Marks	Comments
A correct explanation, e.g. ‘He has divided by 2 not divided by a half’. ‘He has worked out a half of 20 (not divided 20 by a half)’. ‘He should have multiplied by 2’. ‘He should have multiplied not divided’. ‘He should have divided by a half (not by 2)’	E1	Accept ‘20 ÷ ½ = 40’ or ‘20 × 2 = 40’. Award E0 for: a correct explanation given but later contradicted an unsupported 40 ‘he shouldn’t have divided by 2’ ‘there are more than 10 halves in 20’ a correct explanation given with an incorrect answer to the calculation

Mark scheme (c)

Scheme	Marks	Comments
A correct explanation, e.g. ‘She hasn’t calculated the difference between the biggest number and the smallest number’. ‘She should have done 20 – 1’	E1	Accept ’20 - 1 = 19’. Allow: ‘range = largest – smallest’ ‘she didn’t put the numbers in order first (before finding the difference between the end numbers)’ ’11 isn’t the biggest number and 7 isn’t the smallest number’ Award E0 for: an unsupported 19 1 – 20 (unless = 19 also seen) ’11 isn’t the biggest number’ ‘7 isn’t the smallest number’ ‘smallest take away the biggest’ a correct explanation given but later contradicted. a correct explanation given with an incorrect answer to the calculation

Scheme

Marks

Comments

A correct explanation, e.g.

‘She hasn’t calculated the difference between the biggest number and the smallest number’.
‘She should have done 20 – 1’

Accept ’20 - 1 = 19’.

Allow:

‘range = largest – smallest’
‘she didn’t put the numbers in order first (before finding the difference between the end numbers)’
’11 isn’t the biggest number and 7 isn’t the smallest number’

Award E0 for:

an unsupported 19
1 – 20 (unless = 19 also seen)
’11 isn’t the biggest number’
‘7 isn’t the smallest number’
‘smallest take away the biggest’
a correct explanation given but later contradicted.
a correct explanation given with an incorrect answer to the calculation

Mark scheme (d)

Scheme	Marks	Comments
A correct explanation, e.g. ‘They should halve (1/5 of the number to work out 1/10 of the number)’. ‘They should divide by 2’. ‘They should multiply by 5 then divide by 10’.	E1	Accept equivalent explanations.