The cost of 36 kg of rice last year was ₹ 1044 and the cost of 24 kg of rice this year is ₹ 768. What is the difference between the cost per kg of rice last year and the cost per kg of rice this year?

### Concept & Formula This problem requires computing individual unit rates (cost per kg) for two distinct periods and finding their arithmetic variance. $$ \text{Unit Cost} = \frac{\text{Total Cost}}{\text{Total Quantity}} $$ ### Step-by-Step Solution * **Given:** * Last year: Cost of 36 kg = ₹ 1044 * This year: Cost of 24 kg = ₹ 768 * **Calculation:** * Find the cost per kg last year: $$ \text{Cost per kg}_{\text{last year}} = \frac{1044}{36} = \text{₹ } 29 $$ * Find the cost per kg this year: $$ \text{Cost per kg}_{\text{this year}} = \frac{768}{24} = \text{₹ } 32 $$ * Calculate the absolute difference between the two unit prices: $$ \text{Difference} = 32 - 29 = \text{₹ } 3 $$ ### Exam Strategy & Shortcut Simplify through rapid division: * $\frac{1044}{36}$: Divide both parts by 9 first $\rightarrow \frac{116}{4} = 29$. * $\frac{768}{24}$: Divide both parts by 8 first $\rightarrow \frac{96}{3} = 32$. * Subtract directly: $32 - 29 = 3$. ### Common Pitfall Avoid mixed combinations, such as subtracting quantities or total values before dividing. The unit rates must be evaluated separately before applying the subtraction. ### Final Answer **Therefore, the correct answer is ₹ 3.**