Higher November 2018 Paper 3 Q14
14 \(y\) is inversely proportional to \(x^3\)
\(y = 44\) when \(x = a\)
Show that \(y = 5.5\) when \(x = 2a\) (3)
| Answer | Mark | Mark scheme |
|---|---|---|
| Evidence of solution | M1 | for constructing an equation eg \(y \propto \dfrac{1}{x^3}\) or eg \(y = \dfrac{k}{x^3}\) oe |
| M1 | for substituting in the values \(a\) and 44 into \(y = \dfrac{k}{x^3}\) | |
| C1 | for a complete method to use the equation, the value of \(k\) and \(x = 2a\) to show \(y = 5.5\) eg \((2a)^3 y = 44a^3\) and \(y = 44a^3 \div 8a^3 = 5.5\) |
Additional guidance
Must show all steps clearly