Solved UPSC CDS/OTA Question
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Q · Mixture and AlligationMedium · 45s
A mixture of 40 liters has 30% alcohol. How much alcohol should be added to make it 50% alcohol?
TopicMixture and Alligation
Question Typemultiple choice
DifficultyMedium
Marking+1 / −0.33
Test Duration30 min
Step-by-Step Solution
The complete worked solution.
Every step explained - no skipped algebra.
Initial alcohol = 30% of 40 = 12 liters
Let x liters of pure alcohol be added.
New total = 40 + x
New alcohol = 12 + x
Required percentage = 50%
Set up:
(12 + x) / (40 + x) = 0.5
→ 12 + x = 0.5(40 + x)
→ 12 + x = 20 + 0.5x
→ 0.5x = 8
→ x = 16
Final Answer: Option B - 16 liters