Subject: General Aptitude · Chapter: Alligation or Mixture · Exam: · Marks: · Difficulty:
How many liters of water should be added to a 30 litre mixture of milk and water containing milk and water in the ratio of 7 : 3 such that the resultant mixture has 40% water in it? [SSC—Junior Associates (Pre.) Exam, 2016]
(a)5
(b)2
(c)3
(d)8 ALLIGATION OR MIXTURE
Answer
Answer (as printed): A
Explanation
Total quantity of mixture = 30 litres 7 Quantity Milk in the mixture = × 30 litre = 21 litres 7+3 3 and quantity water in the mixture = × 30 litre = 9 litres 7+3 Let water to be mixed ‘a’ litre 40 Then ( 30 + a ) × =9+a 100 or 120 + 4a = 90 + 10a or 120 – 90 = 10a – 4a 30 = 6a ⇒a=5 Hence, 5 litres water mixed in the mixture.
Explanation as extracted from the printed page; notation may be imperfect.