Question

A sample of clay was partially dried and then contained 50% silica and 7% water. The original clay contained 12% water. The percentage of silica in the original sample is ______%.

Options

• 45.68

• 47.31

• 49.26

• 51.34

Answer 1

A sample of clay was partially dried and then contained 50% silica and 7% water. The original clay contained 12% water. The percentage of silica in the original sample is 47.31%.

Explanation:

Partially dried clay sample:

Silica + Water + Impurities = 100

50 + 7 + Impurities = 100

Impurities = 100 − 57

Impurities = 43%

Original clay:
x + 12 + Impurities = 100

Impurities = (100 − 12) − x

Impurities = (88 − x)%

`50/43 = "x"/(88 - "x")`

x = 47.3%