Understanding Gold Purity and Carats

Gold is often mixed with other metals like copper, silver, or zinc to make it harder and more durable for jewelry. The purity of gold is measured using the **carat** system. In this system, 24-carat gold is considered 100% pure gold.

Calculating Purity for 18-Carat Gold

The question asks for the percentage of pure gold in 18-carat gold. Here's how we can calculate it:

• The total scale for gold purity is 24 parts (representing 100% pure gold).
• 18-carat gold means that out of these 24 parts, 18 parts are pure gold.
• To find the percentage, we use the following formula: $$ \text{Percentage Purity} = \left( \frac{\text{Carats of Gold}}{\text{Total Carat Scale}} \right) \times 100\% $$
• Substituting the values for 18-carat gold: $$ \text{Percentage Purity} = \left( \frac{18}{24} \right) \times 100\% $$
• Simplify the fraction: $$ \frac{18}{24} = \frac{3 \times 6}{4 \times 6} = \frac{3}{4} $$
• Convert the fraction to a percentage: $$ \frac{3}{4} \times 100\% = 0.75 \times 100\% = 75\% $$

Therefore, 18-carat gold contains 75% pure gold.

Relating Calculation to Options

Based on our calculation, the percentage of pure gold in 18-carat gold is 75%. This matches the second option provided.