Mixture & Alligation

JKSSB Sub-Inspector (Telecommunication) · Basic Numeracy · 31 practice questions with answers and explanations: 8 Easy, 11 Medium, 12 Hard.

Sample questions

Sample Easy question 1

A mixture of milk and water is in the ratio 3:1. If the total mixture is 40 litres, find the quantity of water.

  1. 8
  2. 9
  3. 10
  4. 12
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Answer: C. Water = (1/4) × 40 = 10 litres.

Sample Medium question 2

In what ratio should tea worth Rs. 20/kg be mixed with tea worth Rs. 30/kg to get a mixture worth Rs. 24/kg?

  1. 2:3
  2. 3:2
  3. 1:2
  4. 4:5
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Answer: B. By alligation: (30-24):(24-20) = 6:4 = 3:2.

Sample Hard question 3

A vessel contains 40 litres of pure milk. 8 litres is removed and replaced with water, and this process is repeated once more. Find the quantity of milk left after the second replacement.

  1. 24 litres
  2. 24.8 litres
  3. 25.6 litres
  4. 26.4 litres
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Answer: C. After each replacement, the remaining fraction is (1 - 8/40) = 0.8. After 2 replacements: 40 × 0.8² = 40 × 0.64 = 25.6 litres.

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