Higher June 2023 Paper 4 Q15
15 \(y\) is inversely proportional to the square root of \(x\).
\(y = 7\) when \(x = 144\).
Find the value of \(y\) when \(x = 16\). [3]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| 21 | 3 | M1 for \(y = \frac{k}{\sqrt{x}}\) oe e.g. \(7 = \frac{k}{\sqrt{144}}\) (\(k\) anywhere) M1 for \(y = \frac{their\ k}{\sqrt{16}}\) or B1 for \(k = 84\) | Alternative : M1 for 144 ÷ 16 [= 9] M1 for \(7 \times \sqrt{their\ 9}\) Note : Direct proportionality leads to an answer of \(\frac{7}{3}\) oe |