Numeracy Higher June 2025 Unit 1 Q11
11. Harri and Alys are learning about diluting liquids.
They mix 300 ml of water with 200 ml of acetic acid to make 500 ml of diluted acetic acid.
Water has a density of 1 g/ml.
Acetic acid has a density of 1·05 g/ml.
Calculate the density of the diluted acetic acid that Harri and Alys have made.
Give your answer as a decimal. [4]
Density of the diluted acetic acid is …………… g/ml
| Scheme | Marks | Comments |
|---|---|---|
| (Mass =) 300×1 + 200×1.05 | M1 | |
| = 510 (g) | A1 | May be seen as 5.1 (g) if 5 ml considered (i.e. M1A1 for 3×1 + 2×1.05 = 5.1) |
| (Density of new liquid =) \(\dfrac{510}{500}\) or \(\dfrac{5.1}{5}\) or equivalent | M1 | FT ‘their derived 5(.)10’ |
| = 1.02 (g/ml) | A1 | Answer space takes precedence Do not accept fractions or mixed numbers If no marks awarded, SC1 for appropriate sight of (2(.)00×1.05 =) 210 or 2.1 |