Solved UPSC CDS/OTA Question
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Q · Ratio and ProportionMedium · 45s
A dishonest shopkeeper mixed 1 litre of water for every 3 litres of petrol and thus made up 36 litres of petrol. If he now adds 15 litres of petrol to the mixture, find the ratio of petrol and water in the new mixture.
TopicRatio and Proportion
Question Typemultiple choice
DifficultyMedium
Marking+1 / −0.33
Test Duration30 min
Step-by-Step Solution
The complete worked solution.
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Water : Petrol = 1 : 3 So, total parts = 1 + 3 = 4 parts
Now, total volume = 36 litres → Each part = 36 ÷ 4 = 9 litres → Water = 1 part = 9 litres → Petrol = 3 parts = 27 litres
Add 15 litres of petrol
New petrol amount = 27 + 15 = 42 litresWater remains = 9 litres
Final ratio
Petrol : Water = 42 : 9Simplify → divide both by 3 → 14 : 3
Final Answer: Option B - 14 : 3