5 out of 2250 parts of earth is sulphur. What is the percentage of sulphur in earth?

### Concept & Formula This problem requires converting a standard ratio or fraction into a percentage. The concept is identical to standard percentage formulas: isolate the specific part, divide it by the total parts, and multiply the outcome by $100$. $$ \text{Percentage} = \left( \frac{\text{Given Parts}}{\text{Total Parts}} \right) \times 100 $$ ### Step-by-Step Solution **Given:** * Sulphur parts = $5$ * Total parts of earth = $2250$ **Calculation / Deduction:** * Construct the fraction representing the ratio of sulphur to the total: $$ \frac{5}{2250} $$ * Simplify the fraction by dividing the numerator and the denominator by $5$: $$ \frac{1}{450} $$ * To convert this fraction into a percentage, multiply by $100$: $$ \frac{1}{450} \times 100 $$ * Simplify the expression by cancelling a zero from the numerator and denominator: $$ \frac{10}{45} $$ * Further simplify by dividing both numbers by their greatest common divisor, which is $5$: $$ \frac{2}{9} $$ * The result is $\frac{2}{9}\%$. The options represent the numerical value of the percentage. ### Exam Strategy & Shortcut Write down the expression directly as $\frac{5}{2250} \times 100$. Cancel the zeroes immediately to get $\frac{50}{225}$. Knowing your multiples of $25$ is extremely helpful here. $50$ is $2 \times 25$, and $225$ is $9 \times 25$. Cancelling the $25$ from the top and bottom instantly leaves you with $\frac{2}{9}$. ### Common Pitfall A very common mistake is confusing the fractional part with the percentage itself. Students might simplify $\frac{5}{2250}$ to $\frac{1}{450}$ and then incorrectly look for that answer, forgetting the final crucial step of multiplying by $100$ to convert it to a percentage format. ### Final Answer Therefore, the correct answer is **$\frac{2}{9}$**.