Mixtures & Alligations Question Answers

Mixtures and Alligations - Quant/Math - CAT 2008

Question 4 the day: November 14, 2003

The question for the day is from the topic of Mixtures and Alligations.

From a cask of milk containing 30 litres, 6 litres are drawn out and the cask is filled up with water. If the same process is repeated a second, then a third time, what will be the number of litres of milk left in the cask?

 

(1)	0.512 liters			(2)	12 liters
(3)	14.38 liters			(4)	15.36 liters

Correct Answer - (4)
 

---

Solution:


The problem can be solved by traditional method but it is cumbersome process to do that. The problem is simple if its solution is simpler. Hence we will go for a simpler solution for this kind of problem.

There is a short cut method to find the Quantity of milk left after n^th operation

It is given by [(x � y)/x]ⁿ of the whole quantity, where x is initial quantity of milk in the cask y is the quantity of milk withdrawn in each process and n is the number of process.

Hence from the above rule it can be say that

Quantity of milk left after the 3^rd operation = [(30 � 6)/30]³ * 30 = 15.36 liters.