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Bob makes dry concrete by mixing cement, sand and stone in the ratio 1 : 2 : 3 by weight - OCR - GCSE Maths - Question 4 - 2019 - Paper 4
Question 4
Bob makes dry concrete by mixing cement, sand and stone in the ratio 1 : 2 : 3 by weight. He buys the cement, sand and stone in bags as shown in this table. | Mater... show full transcript
Worked Solution & Example Answer:Bob makes dry concrete by mixing cement, sand and stone in the ratio 1 : 2 : 3 by weight - OCR - GCSE Maths - Question 4 - 2019 - Paper 4
Step 1
Show that Bob buys 500 kg of sand.
Answer
To find the total weight of the dry concrete Bob needs, we calculate:
Total weight for 50 bags = Number of bags × Weight per bag
egin{align*}
Total ext{ } weight &= 50 ext{ bags} imes 30 ext{ kg/bag}
&= 1500 ext{ kg}
ext{ }
ext{Next, we find the weight of each component in the ratio 1:2:3:}
ext{Total ratio parts} = 1 + 2 + 3 = 6
ext{ }
ext{Now, calculate the weight of sand:}
ext{Weight of sand} = rac{2}{6} imes 1500 ext{ kg} = 500 ext{ kg}
ext{ }
Thus, Bob needs to buy 500 kg of sand.