posted by Kay .
Suppose that you calculated the mass percent of sand in the mixture to be 42%, though the original mixture really contained only 35% sand. How could you explain these results?
When you put the mixture together it had ro of had another compound of sand in the befinning which means that both had consentrations of sand in them
Another explanation is that the "dried" sand, before weighing in the last step, was not dry. The extra water was reported as sand.