What percent of water must be mixed with honey so as to gain 20% by selling the mixture at the cost price of honey?

A. 20%
B. 10%
C. 5%
D. 4%

Answer: A. 20%

Explanation:

Let:

- C be the cost price per unit of honey.

- The amount of honey used is 100 units.

The total cost price of the honey is C × 100.

Step 1: Selling Price Calculation

We want to sell the mixture at a 20% profit, so the selling price of the mixture should be: 1.20 × C × 100

Step 2: Total Selling Price of Mixture

The total selling price is also given by: (100 + W) × C

Where W is the amount of water.

Step 3: Set the Selling Prices Equal

1.20 × C × 100 = (100 + W) × C

Step 4: Simplify the Equation

1.20 × 100 = 100 + W

120 = 100 + W

Step 5: Solve for W

W = 120 - 100 = 20

So, the amount of water to mix is 20 units.

Step 6: Calculate the Percentage of Water

The percentage of water is: (20 / 100) × 100 = 20%

Conclusion:

The percentage of water to mix is 20%.