The owner of a boutique decides to calculate the percentage of customers who purchase hats. If 40 percent of the store's customers decide to purchase items, and of those customers 15 percent purchase hats, what percent of the store's customers purchase hats?

Concept & Logic This problem requires calculating a percentage of a percentage (successive percentage). You simply multiply the two percentages to find the final fraction of the total whole. $$ \text{Overall Percentage} = (\text{Fraction 1}) \times (\text{Fraction 2}) \times 100 $$ Step-by-Step Solution * Given: The percentage of customers who buy any item is $40\%$. * Given: The percentage of those buyers who specifically purchase hats is $15\%$. * We need to find $15\%$ of $40\%$. * Convert percentages to decimals to calculate: $40\% = 0.40$ and $15\% = 0.15$. * Calculation: $0.15 \times 0.40 = 0.06$. * Convert the resulting decimal back to a percentage: $0.06 \times 100 = 6\%$. Exam Strategy & Shortcut Assume the total number of customers is $100$. Customers who purchase items = $40$. Customers who purchase hats = $15\%$ of $40 = \frac{15}{100} \times 40 = 6$. Since the base is $100$, $6$ customers exactly represents $6\%$. Common Pitfall Adding the percentages together ($40\% + 15\% = 55\%$) or subtracting them instead of realizing that the second percentage is a subset of the first. Always pay attention to the phrase "of those customers." Final Answer Therefore, the correct answer is **6%**.