High School

Bob the builder is making 480 kg of concrete mix. Concrete is made by mixing cement, sand, and gravel in the ratio [tex]1:3:4[/tex]. How much sand does he need?

Answer :

To solve the problem, follow these steps:

1. The concrete mix is made in the ratio [tex]$1:3:4$[/tex], which means the total number of parts is:

[tex]$$
1 + 3 + 4 = 8.
$$[/tex]

2. The total mix weighs 480 kg. To find the weight corresponding to one part, divide the total weight by the number of parts:

[tex]$$
\text{Weight per part} = \frac{480}{8} = 60 \text{ kg}.
$$[/tex]

3. Since the ratio for sand is 3, the weight of sand needed is:

[tex]$$
\text{Weight of sand} = 3 \times 60 = 180 \text{ kg}.
$$[/tex]

Thus, Bob needs [tex]$180 \text{ kg}$[/tex] of sand.