GMAT Quantitative - Alligations and Mixtures (2)

Description

Alligations and Mixtures is a quantitative aptitude topic about mixing ingredients with different properties to create a new mixture. 🧪

The main tool is the Rule of Alligation, a visual method to find the ratio in which two ingredients must be mixed to achieve a desired average value.

How it works:

1. Place the two ingredient values (C1​, C2​) on the left and right.

2. Place the desired mixture value (Cm​) in the middle.

3. The ratio of the quantities is the difference between these values, cross-wise:

   • Quantity 1 : Quantity 2 = $(C_2-C_m):(C_m-C_1)$

Example:

To mix a ₹100/kg tea and a ₹150/kg tea to get a ₹120/kg blend, the ratio is:

(150−120):(120−100)=30:20=3:2. ☕

This concept is essential for problems involving mixing liquids, calculating average costs, or successive replacements. It's a quick way to solve weighted average problems. 🤔