Higher June 2018 Paper 6 Q15
15 Ratna invests £1200 for 2 years in a bank account paying \(r\) % per year compound interest.
At the end of 2 years, the amount in the bank account is £1379.02.
Calculate \(r\). [4]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| 7.2[0] or 7.19[9…] nfww | 4 | M3 for \(\sqrt{\dfrac{1379.02}{1200}}\) oe soi by 1.067[…] to 1.072{…] OR M2 for \(\dfrac{1379.02}{1200}\) oe soi by 1.14 to 1.15 OR M1 for \(1200x^2 = 1379.02\) Trials or no working: SC4 for correct answer 7.2[0] or 7.19[9…] on answer line OR SC3 for \(1200 \times 1.072[0]^2 = 1379.02\) or \(1200 \times 1.0719[9\ldots]^2 = 1379.02\) OR SC1 for use of \(1200x^2\) oe | Condone % symbol with correct answer. Warning: 1200 ÷ 179.02 = 6.7 Allow \(\left(1 + \dfrac{r}{100}\right)\) or any letter, including \(r\), in place of \(x\). |