1MA0 Foundation November 2012 Paper 1 Q29
*29 Talil is going to make some concrete mix.
He needs to mix cement, sand and gravel in the ratio 1 : 3 : 5 by weight.
Talil wants to make 180 kg of concrete mix.
Talil has
15 kg of cement
85 kg of sand
100 kg of gravel
Does Talil have enough cement, sand and gravel to make the concrete mix? (4)
| Working | Answer | Mark | Notes |
|---|---|---|---|
| \(180 \div 9 \times 1 : 180 \div 9 \times 3 : 180 \div 9 \times 5\) = 20 : 60 : 100 Not enough cement (but enough sand and enough gravel) OR \(1 \times 15 : 3 \times 15 : 5 \times 15\) = 15 : 45 : 75 \(15 + 45 + 75 = 135\) (<180) Not enough cement (to make 180kg of concrete) | No + reason | 4 | M1 for \(180 \div (1 + 3 + 5)\) (=20) or 3 multiples of 1 : 3 : 5 M1 for \(1 \times \text{`}20\text{'}\) or \(3 \times \text{`}20\text{'}\) or \(5 \times \text{`}20\text{'}\) or 20 seen or 60 seen or 100 seen A1 for (Cement=) 20, (Sand=) 60, (Gravel=) 100 C1 ft (provided both Ms awarded) for not enough cement oe OR M1 for (\(1 \times 15\) and) \(3 \times 15\) and \(5 \times 15\) or \(9 \times 15\) or sight of the numbers 15, 45, 75 together. M1 for ‘15’ + ‘45’ + ‘75’ A1 for 135 (<180) C1 ft (provided both Ms awarded) for not enough cement oe |