The density and strength of concrete are determined by the ratio of cement and aggregate (aggregate is sand, gravel, or crushed stone). Suppose that a contractor has 410 ft³ of a dry concrete mixture that is 70% sand by volume. How much pure sand must be added to form a new mixture that is 80% sand by volume? The contractor needs ft³ of pure sand to form the resulting mixture.
Added by Timothy B.
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Since the mixture is 70% sand, we multiply 410 in³ by 0.70 to get 287 in³. This is the amount of sand in the original mixture. Show more…
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