A batch of concrete is made by mixing 1 part cement, 2.5 parts sand, and 3.5 parts gravel. How many pounds of sand and gravel are needed to make 300 pounds of cement?
2.5/7 = x/300 for sand
3.5/7 = x/300 for gravel
In each case, solve for x.
I figured it out, and actually you multiply the 2.5 by 300 and then the 3.5 by 300 to get the amount of sand and gravel!!
2.5x300=750. 3.5x300=1,050
To find out how many pounds of sand and gravel are needed to make 300 pounds of cement, we need to understand the ratios given. The ratio given is 1 part cement to 2.5 parts sand to 3.5 parts gravel. This means that for every 1 part of cement, we need 2.5 parts of sand and 3.5 parts of gravel.
To solve this problem, we will first find the total number of parts in the given ratio. The total number of parts is obtained by adding the individual ratios of sand and gravel, which are 2.5 and 3.5 respectively.
Total number of parts = 2.5 (for sand) + 3.5 (for gravel) = 6
Next, we will find the ratio of cement to the total number of parts. This will give us the proportion of cement in each part.
Cement ratio = 1 part (cement) / 6 (total number of parts) = 1/6
Now, we can find the amount of cement in 300 pounds of the concrete batch.
Amount of cement = Cement ratio * Total weight of concrete = (1/6) * 300 = 50 pounds
Since the ratio of cement to sand and gravel is 1:2.5:3.5, the respective amounts of sand and gravel can be calculated by multiplying the amount of cement by the corresponding ratios.
Amount of sand = (2.5 parts / 6 parts) * Amount of cement = (2.5/6) * 50 = 20.83 pounds (approximately)
Amount of gravel = (3.5 parts / 6 parts) * Amount of cement = (3.5/6) * 50 = 29.17 pounds (approximately)
Therefore, to make 300 pounds of cement, you would need approximately 20.83 pounds of sand and 29.17 pounds of gravel.