Foundation November 2017 Paper 2 Q22
22
(a) Beth is given the following question.
| Work out \(4.1 \times 10^5 \times 3 \times 10^2\). Give your answer in standard form. |
This is Beth’s answer to the question.
\[12.3 \times 10^7\]Explain why Beth’s answer is incorrect. [1]
(b) Show that\[4.5 \times 10^2 + 7.3 \times 10^3 = 7.75 \times 10^3.\]
[2]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| Valid explanation | 1 | Such as ‘because it is not in standard form’ | eg because 12.3 is not a number between 1 and 10 See Appendix |
Appendix
Exemplar responses for Q22a
| Response | Mark |
|---|---|
| The first number eg (12.3) has to be between (1-10) so it should be (1.23) | 1 |
| It should be 1.23 x 10\(^8\) not 12.3 x 10\(^7\) | 1 |
| It has to be a number between 1 – 10, 1.23 x 10\(^8\) would be the correct answer | 1 |
| Because the first number has to be a one digit number before the decimal place | 1 |
| Because the decimal number always has to be below 10 | 1bod |
| Because the number needs to be between 1 – 10 | 0 |
| This is not in standard form as you still have the decimal. | 0 |
| She didn’t give the answer in standard form and she added (10\(^5\) +10\(^2\)) wrong (statement in bold would score 1) | 0 |
| because standard form states that the number has to be between one and nine | 0 |
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| 450 + 7300 | M1 | or \(0.45 \times 10^3 + 7.3 \times 10^3\) or \(4.5 \times 10^2 + 73 \times 10^2\) | Or correct use of a common power of 10 |
| = 7750 = \(7.75 \times 10^3\) | A1 | or complete working leading to \(7.75 \times 10^3\) | |