Due to reduction in books price by 10%. The number of books sold increased by 35%. What was the percentage increase in revenue?

To calculate the percentage increase in revenue, you can use the following formula:

Percentage Increase = [(New Value - Old Value) / Old Value] * 100%

In this case, the old value represents the initial revenue before the price reduction, and the new value represents the revenue after the price reduction and increase in sales.

Let's assume the initial revenue is represented by "R" (you can use any value), and the price reduction is 10%, which means the new price is 90% of the old price.

So, the new revenue (after price reduction) can be expressed as:

New Revenue = (0.90 * R) * 1.35

Here, 0.90 represents the 90% of the old price, and 1.35 represents a 35% increase in sales (135% of the old quantity).

Now, let's calculate the percentage increase in revenue:

Percentage Increase = [(New Revenue - Old Revenue) / Old Revenue] * 100%

Percentage Increase = [(0.90 * R * 1.35 - R) / R] * 100%

Simplify:

Percentage Increase = [(1.215 * R - R) / R] * 100% Percentage Increase = [(0.215 * R) / R] * 100%

The "R" terms cancel out:

Percentage Increase = 0.215 * 100%

Percentage Increase = 21.5%

So, the percentage increase in revenue is 21.5%. Since none of the provided options match this value, the correct answer is “None of these.”