Question

A sample of clay was partially dried. It was found to contain $50\%$ silica and $7\%$ water. The original clay contained $12\%$ water. If $x$ percentage of silica is present in the original sample then, determine the value of $10x$.

• A. $473$
• B. $470$
• C. $480$
• D. None of these

Answer 1

The correct option is A $473$

On drying, the weight of water changes but the ratio of silica with other materials remains constant. If $x$ is the $\%$ of silica in the original sample, $(88-x)$ is the weight of the materials other than water and silica.
$\therefore \frac{x}{88-x}=\frac{50}{43}\Rightarrow x=47.3$
Therefore, $10x=473$.