Foundation November 2022 Paper 2 Q9

(a) By writing each number correct to 1 significant figure, find an estimate for \(79.8 \times 3.1\). [2]

(b) Jamie works out \(79.8 \times 3.1\) on a calculator.
Jamie’s answer is 2473.8.

Do you think Jamie has used their calculator correctly?
Explain why.

.................... because ........................................ [1]

Answer	Marks	Part marks and guidance
240 with working	2	B1 for rounded value of 80 or 3 If 0 scored SC1 for 80.0 and 3.0 and 240.0 as answer	For 2 marks 80 and 3 must be seen

Mark scheme (b)

Answer	Marks	Part marks and guidance
No oe and [because] the answer should be close to 240 oe	1		Eg No his answer is ten times too big No the decimal point is in the wrong place See AG

Appendix Q9b

	Response	Mark
	No
1	The answer should be 247.38	1
2	The decimal point should be between the 7 and 3	1
3	The number is a lot higher than my estimate. I think she placed a decimal point wrong (The first part is not enough without seeing what their estimate is, ‘placed decimal point wrong’ scores the mark)	1
4	His answer should be in 200s not 2000s he must have placed decimal incorrectly	1
5	There should be 2 numbers behind the decimal place and not one	1
6	Because if you do \(80 \times 3\) you’ll get 240 (implies the answer is 10 times too big)	1
7	it should be closer to 240 (This is the correct estimate, so no need for calculation to be shown here)	1
8	His answer was in thousands which is too large (with it should be in the hundreds would have scored the mark)	0
9	Has not put decimals in	0
10	His answer is too high and shouldn’t have a decimal at the end (First part of answer is not enough to score and ‘shouldn’t have a decimal at the end’ is incorrect)	0
11	The answer that Jamie got is bigger than the estimate by 1 significant figure	0
12	There is only one two digit number so it cannot be above 1000	0
13	It would be less than 2473.8 due to \(80 \times 3\) (if the candidate had written = 240, this would be enough)	0
14	his answer is significantly larger	0
15	there is no way it can be higher than 300 (not enough as we need to see the calculation of their ‘estimate’ of 300)	0
16	The place value is not in the correct position (‘place value’ not an equivalent for decimal point)	0