1. Problem statement: Rohan ordered 5 kg of premium coffee and some additional kilograms of ordinary coffee. The price per kg of premium coffee is three times that of ordinary coffee. When the quantities were swapped, the bill increased by 40%. We need to find the ratio of the original quantity of premium coffee to the original quantity of ordinary coffee. 2. Let the price per kg of ordinary coffee be $x$. Then the price per kg of premium coffee is $3x$. 3. Let the original quantity of ordinary coffee be $y$ kg. Given premium coffee quantity is 5 kg. 4. Original bill = (price of premium coffee) + (price of ordinary coffee) = $3x \times 5 + x \times y = 15x + xy$. 5. After swapping quantities, premium coffee quantity becomes $y$ kg and ordinary coffee quantity becomes 5 kg. 6. New bill = $3x \times y + x \times 5 = 3xy + 5x$. 7. The new bill is 40% more than the original bill, so: $$3xy + 5x = 1.4(15x + xy)$$ 8. Divide both sides by $x$ (assuming $x \neq 0$): $$3y + 5 = 1.4(15 + y)$$ 9. Expand right side: $$3y + 5 = 21 + 1.4y$$ 10. Rearrange terms: $$3y - 1.4y = 21 - 5$$ $$1.6y = 16$$ 11. Solve for $y$: $$y = \frac{16}{1.6} = 10$$ 12. The original quantity of premium coffee is 5 kg and ordinary coffee is 10 kg. 13. Therefore, the ratio of premium to ordinary coffee is: $$5 : 10 = 1 : 2$$ Final answer: The ratio of the original quantity of premium coffee to ordinary coffee is $1 : 2$.