Calculating Selling Price with Discount Changes

This problem involves finding a new selling price based on a change in the discount percentage applied to the original list price.

Method: Using Ratio of Discounts

We can solve this efficiently by understanding the relationship between selling price, list price, and discount.

1. Identify discount factors:
   • A 10% discount means the selling price is 100% - 10% = 90% of the list price. Use a factor of $0.90$.
   • A 20% discount means the selling price will be 100% - 20% = 80% of the list price. Use a factor of $0.80$.
2. Set up the ratio: Let the original selling price be $SP_1$ and the new selling price be $SP_2$. Let the list price be $LP$. We know: $SP_1 = LP \times (1 - 0.10) = LP \times 0.90$ $SP_2 = LP \times (1 - 0.20) = LP \times 0.80$ The ratio of the selling prices is equal to the ratio of their discount factors: $ \frac{SP_2}{SP_1} = \frac{LP \times 0.80}{LP \times 0.90} = \frac{0.80}{0.90} = \frac{8}{9} $
3. Calculate the new selling price ($SP_2$): Substitute the known $SP_1 = ₹36$: $ \frac{SP_2}{₹36} = \frac{8}{9} $ Solve for $SP_2$: $ SP_2 = ₹36 \times \frac{8}{9} $ $ SP_2 = ₹4 \times 8 $ $ SP_2 = ₹32 $

Therefore, a selling price of ₹32 results in a 20% discount on the list price.