Higher November 2018 Paper 2 Q15

15 The volume of a medal is 45 cm³

The medal is made from copper and tin.

volume of copper : volume of tin = 22 : 3

The density of copper is 8.96 g/cm³
The density of tin is 7.31 g/cm³

Work out the mass of the medal. [4 marks]

Mark scheme

Answer	Mark	Comments
Alternative method 1
\(45 \div (22 + 3)\) or \(45 \div 25\) or 1.8	M1	oe eg \(\dfrac{45}{25}\)
\(22 \times \text{their } 1.8\) or 39.6 or \(3 \times \text{their } 1.8\) or 5.4	M1dep
\(\text{their } 39.6 \times 8.96 + \text{their } 5.4 \times 7.31\) or \([354, 355] + [39, 40]\)	M1dep
394.29 or 394.3	A1
Alternative method 2
\(45 \div (22 + 3)\) or \(45 \div 25\) or 1.8	M1	oe eg \(\dfrac{45}{25}\)
\(\text{their } 1.8 \times 8.96\) or [16.1, 16.13] or \(\text{their } 1.8 \times 7.31\) or [13.1, 13.2]	M1dep
\(\text{their } [16.1, 16.13] \times 22\) \(+\; \text{their } [13.1, 13.2] \times 3\) or \([354, 355] + [39, 40]\)	M1dep
394.29 or 394.3	A1
Alternative method 3
\(45 \div (22 + 3)\) or \(45 \div 25\) or 1.8	M1	oe eg \(\dfrac{45}{25}\)
\(22 \times 8.96\) or [197, 197.12] or \(3 \times 7.31\) or [21.9, 22]	M1
\(\text{their } [197, 197.12] \times \text{their } 1.8\) \(+\; \text{their } [21.9, 22] \times \text{their } 1.8\) or \([354, 355] + [39, 40]\)	M1dep	oe dep on M1M1
394.29 or 394.3	A1

Allow up to M2 even if not subsequently used

Ignore units throughout