Mixtures and Alligation  Quant/Math 
Question 4 the day:
October 11, 2002
The question for the day is from the topic of Mixtures and Alligation.
 How many kgs of Basmati rice costing Rs.42/kg should a shopkeeper mix with 25 kgs of ordinary rice costing Rs.24 per kg so that he makes a profit of 25% on selling the mixture at Rs.40/kg?
(1) 
20 kgs 

(2) 
12.5 kgs 

(3) 
16 kgs 

(4) 
200 kgs 
Correct Answer  (1)
Solution:
Let the amount of Basmati rice being mixed be x kgs. As the trader makes 25% profit by selling the mixture at Rs.40/kg, his cost /kg of the mixture = Rs.32/kg.
i.e. (x * 42) + (25 * 24) = 32 (x + 25)
=> 42x + 600 = 32x + 800
=> 10x = 200 or x = 20 kgs.
