Higher June 2017 Paper 1 Q8
8 \(x\) km/h \(= y\) mph
Use \(\quad 8\) km/h \(= 5\) mph \(\quad\) to write a formula for \(y\) in terms of \(x\). [2 marks]
| Answer | Mark | Comments |
|---|---|---|
| \(\dfrac{y}{x} = \dfrac{5}{8}\) or \(\dfrac{x}{y} = \dfrac{8}{5}\) or \(8y = 5x\) or \(\dfrac{5x}{8}\) or \(0.625x\) or \((x =)\ \dfrac{8y}{5}\) or \((x =)\ 1.6y\) or \(y = \mathrm{k}x\) and \(\mathrm{k} = \dfrac{5}{8}\) or \(8 \div 5\) incorrectly evaluated and then \(y = \dfrac{x}{\text{their incorrect evaluation}}\) | M1 | oe |
| \(y = \dfrac{5x}{8}\) | A1 | oe in form \(y = f(x)\) or \(f(x) = y\) eg \(y = 0.625x\) or \(y = \dfrac{x}{1.6}\) or \(y = 5x \div 8\) or \(y = x \div (8 \div 5)\) or \(y = x \div 8 \times 5\) |
Additional guidance
| \(y = \dfrac{5}{8} \times x\) or \(y = \dfrac{x}{8} \times 5\) or \(y = x \div 1.6\) | M1A1 |
| \(y8 = x5\) or \((y =)\ \dfrac{x5}{8}\) or \((y =)\ x\dfrac{5}{8}\) or \(y = \dfrac{5}{8}\) of \(x\) | M1A0 |
| Condone units for M1 only | |
| Do not ignore further work eg \(y = x \div (8 \div 5)\) then \(y = x \div 8 \div 5\) | M1A0 |