Three parts of alcohol A is mixed with two parts of alcohol B and sold at $110 per liter at a 10% profit. If alcohol A cost $20 more per liter than alcohol B, what is the price of alcohol A per liter?
The Usual Method
Let price of alcohol A be $a / liter
And that of alcohol B be $b / liter
Also cost of mixture = = $100 (1.1 is due to 10% profit)
By Alligation rule:
Estimated Time to arrive at the answer = 60 seconds.
Note that 3 : 2 can also be written as 6 : 4 or 60 liter and 40 liters. Hence total of 100 liters. Assuming that 100 liters costs $100 ($110 less 10% profit). Of this $100, $60 belongs to alcohol A and $40 to alcohol B. (Since difference of cost of the two alcohols is $20)
This means that the price of alcohol A is a multiple of 6. The only value from the options which is a multiple of 6 is $108 of option ‘4’.
Estimated Time to arrive at the answer = 15 seconds.