Trick â 2 : Percentage Tricks (āĻļāĻ¤āĻā§°āĻž āĻšāĻŋāĻāĻžāĻĒā§° āĻā§āĻļāĻ˛)
1. First Rule – Price Increase
When the price of an item increases by m%, the percentage decrease in consumption required to keep the expenditure unchanged is: (āĻā§āĻ¨ā§ āĻŦāĻ¸ā§āĻ¤ā§ā§° āĻŽā§āĻ˛ā§āĻ¯ m% āĻŦā§āĻĻā§āĻ§āĻŋ āĻš'āĻ˛ā§, āĻŽā§āĻ āĻā§°āĻ āĻāĻā§ ā§°āĻžāĻāĻŋāĻŦāĻ˛ā§ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻŦāĻž āĻāĻĒāĻā§āĻā§° āĻĒā§°āĻŋāĻŽāĻžāĻŖ āĻāĻŋāĻŽāĻžāĻ¨ āĻļāĻ¤āĻžāĻāĻļ āĻāĻŽāĻžāĻŦ āĻ˛āĻžāĻāĻŋāĻŦ ?)
Formula: Decrease in Consumption = m / (100 + m)*100
Example 1:
Q. If the price of mangoes increases by 30%, what percentage decrease in consumption is required to keep the expenditure unchanged ? (āĻāĻŽā§° āĻŽā§āĻ˛ā§āĻ¯ 30% āĻŦā§āĻĻā§āĻ§āĻŋ āĻš'āĻ˛ā§, āĻŽā§āĻ āĻā§°āĻ āĻāĻā§ ā§°āĻžāĻāĻŋāĻŦāĻ˛ā§ āĻāĻŽā§° āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻāĻŋāĻŽāĻžāĻ¨ āĻļāĻ¤āĻžāĻāĻļ āĻāĻŽāĻžāĻŦ āĻ˛āĻžāĻāĻŋāĻŦ ?)
Solution:
Second Rule – Price Decrease
When the price of an item decreases by m%, the percentage increase in consumption required to keep the expenditure unchanged is: (āĻā§āĻ¨ā§ āĻŦāĻ¸ā§āĻ¤ā§ā§° āĻŽā§āĻ˛ā§āĻ¯ m% āĻšā§ā§°āĻžāĻ¸ āĻš'āĻ˛ā§, āĻŽā§āĻ āĻā§°āĻ āĻāĻā§ ā§°āĻžāĻāĻŋāĻŦāĻ˛ā§ āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻŦāĻž āĻāĻĒāĻā§āĻā§° āĻĒā§°āĻŋāĻŽāĻžāĻŖ āĻāĻŋāĻŽāĻžāĻ¨ āĻļāĻ¤āĻžāĻāĻļ āĻŦā§āĻĻā§āĻ§āĻŋ āĻā§°āĻŋāĻŦ āĻ˛āĻžāĻāĻŋāĻŦ ?)
Formula: Increase in Consumption = m/(100 - m) * 100
Example 2:
Q. If the price of ghee decreases by 40%, what percentage increase in consumption is required to keep the expenditure unchanged ? (āĻāĻŋāĻā§° āĻŽā§āĻ˛ā§āĻ¯ 40% āĻšā§ā§°āĻžāĻ¸ āĻš'āĻ˛ā§, āĻŽā§āĻ āĻā§°āĻ āĻāĻā§ ā§°āĻžāĻāĻŋāĻŦāĻ˛ā§ āĻāĻŋāĻā§° āĻŦā§āĻ¯ā§ąāĻšāĻžā§° āĻāĻŋāĻŽāĻžāĻ¨ āĻļāĻ¤āĻžāĻāĻļ āĻŦā§āĻĻā§āĻ§āĻŋ āĻā§°āĻŋāĻŦ āĻ˛āĻžāĻāĻŋāĻŦ ?)
Solution:
Trick
1. Price Increase → Consumption Decrease
2. Price Decrease → Consumption Increase
Note: Expenditure must remain unchanged (āĻŽā§āĻ āĻā§°āĻ āĻāĻā§ āĻĨāĻžāĻāĻŋāĻŦ āĻ˛āĻžāĻāĻŋāĻŦ)āĨ¤