Higher November 2017 Paper 3 Q28
28 \(y = p \times q^{\,x - 1} \qquad\) where \(p\) and \(q\) are numbers.
\(y = 10 \;\) when \(\; x = 1\)
\(y = 0.3125 \;\) when \(\; x = 6\)
Work out the value of \(y\) when \(x = 3\) [5 marks]
| Answer | Mark | Comments |
|---|---|---|
| \(p \times q^{1 - 1} = 10\) or \(p \times q^0 = 10\) or \(p \times q^{6 - 1} = 0.3125\) or \(p \times q^5 = 0.3125\) | M1 | oe |
| \(p = 10\) or \(10 \times q^{6 - 1} = 0.3125\) or \(q^5 = 0.3125 \div\) their 10 or \(q^5 = 0.03125\) | M1dep | |
| \(\sqrt[5]{\text{their } 0.03125}\) or 0.5 | M1dep | oe |
| their \(10 \times\) their \(0.5^2\) or their \(10 \times\) their \(\left(\sqrt[5]{\text{their } 0.03125}\right)^2\) or their \(10 \times\) their \(0.03125^{\frac{2}{5}}\) | M1dep | |
| 2.5 | A1 |