Solved UPSC CDS/OTA Question
A solved UPSC CDS/OTA PYQ - decoded step-by-step.
Solve it the standard way once - then learn the shortcut.
Q · Ratio and ProportionMedium · 45s
The ratio of milk to water in a mixture is 5:2. If 14 liters of water is added, the ratio becomes 5:4. Find the quantity of milk in the original mixture.
TopicRatio and Proportion
Question Typemultiple choice
DifficultyMedium
Marking+1 / −0.33
Test Duration30 min
← Previous questionQ 51 / 51
Step-by-Step Solution
The complete worked solution.
Every step explained - no skipped algebra.
Step 1: Let original milk = 5x, water = 2x
→ Total mixture = 7x
After adding 14 liters of water: → New water = 2x + 14 → New ratio = 5 : 4 So: (5x) / (2x + 14) = 5 / 4
Step 2: Cross-multiply
4 × 5x = 5 × (2x + 14) → 20x = 10x + 70 → 10x = 70 → x = 7
Step 3: Find milk quantity
Milk = 5x = 5 × 7 = 35 liters
Final Answer: Option A - 35 liters