#### 121. A tank contains a mixture of oil and water. Initially, the mixture has 60 liters of oil and 40 liters of water. If 20 liters of the mixture is removed and replaced with 20 liters of pure oil, what is the new ratio of oil to water in the tank?
["#### 121. A tank contains a mixture of oil and water. Initially, the mixture has 60 liters of oil and 40 liters of water. If 20 liters of the mixture is removed and replaced with 20 liters of pure oil, what is the new ratio of oil to water in the tank? \nThis seemingly simple question touches on a common mathematical process with surprising relevance in real-world industries. From automotive maintenance to food processing and chemical blending, understanding how mixtures shift over time shapes efficiency and safety. The shift from oil and water dynamics isn’t just chemistry—it reflects broader trends in resource management and industrial precision, sparking growing curiosity in the US as people seek clearer insights behind everyday processes.", "The growing interest in #### 121. A tank contains a mixture of oil and water reflects a deeper trend: consumers and professionals alike are seeking data-backed clarity about industrial mixtures and their transformations. In a world where efficiency, sustainability, and accuracy define success, understanding such mixtures offers practical value—empowering informed decisions in workplaces and everyday life alike.", "### Why #### 121. A tank contains a mixture of oil and water. Initially, the mixture has 60 liters of oil and 40 liters of water. If 20 liters of the mixture is removed and replaced with 20 liters of pure oil, what is the new ratio of oil to water in the tank?", "This scenario reflects a real-world process known as “component displacement through fluid exchange.” When a portion of a mixed fluid is replaced, it doesn’t simply dilute or dilute—it recalibrates the concentration based on the changing proportions. In this case, removing 20 liters shifts both oil and water in predictable ways, then rebalanced with pure oil to restore volume. This mimics how industries manage storage, purification, and mixing—ensuring consistent quality and efficiency.", "The original tank holds 100 liters total: 60 liters oil, 40 liters water. When 20 liters of the mixture is withdrawn, the removal takes oil and water in the same ratio as the full composition—60:40 or simplified 3:2. So, from 20 liters removed: \n- Oil removed: \( \frac{3}{5} \ imes 20 = 12 \) liters \n- Water removed: \( \frac{2}{5} \ imes 20 = 8 \) liters", "Remaining in tank: \n- Oil: \( 60 - 12 = 48 \) liters \n- Water: \( 40 - 8 = 32 \) liters", "Then, adding 20 liters pure oil: \n- New oil total: \( 48 + 20 = 68 \) liters \n- Water remains: 32 liters", "Final ratio of oil to water: \n\[ \ ext{Oil} : \ ext{Water} = 68 : 32 \]"]
