Higher November 2018 Paper 5 Q11
11 The price of a washing machine is reduced by 20% for a sale.
Afterwards, the sale price is increased by 30%.
Joachim says
The washing machine is now 10% more expensive than before the sale.
Explain Joachim’s error and work out the correct percentage change in the price of the washing machine from before the sale to after the sale. [6]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| He has subtracted the two percentages oe or He used the same price for both percentages oe | 1 | e.g. He does not calculate 30% of the sale price. He calculates 30% of the original price | |
| Increase of 4 [%] | 5 | B4 for answer 104% or for 1.04 seen or M3 for [\(k\) ×] 0.8 × 1.3 oe OR M1 for 0.8 used correctly oe M1 for 1.3 used correctly oe | For 5 marks, condone ‘increase’ omitted Allow method marks if contained in correct method involving any invented starting price e.g. M3 for 400 × 0.8 × 1.3 oe |