To determine the selling price of the mixture when the two qualities of tea are mixed in the ratio 3:4, let's analyze the problem.

Step-by-step Analysis:

1. Key Formula: The cost price of the mixture is calculated using the weighted average formula: $\text{Cost Price of Mixture} = \frac{(3 \times 180) + (4 \times 225)}{3 + 4}$

   Here, 180 (Statement 1) and 225 (Statement 2) are the cost prices of the two qualities, and 3:4 is the ratio.

2. Statement Analysis:

   • Statement 1: Gives the cost price of the first quality of tea ($180 \, \text{Rs/kg}$). Alone, this is insufficient because we don't have the cost price of the second quality of tea or the mixing ratio.
   • Statement 2: Gives the cost price of the second quality of tea ($225 \, \text{Rs/kg}$). Alone, this is insufficient because we don't know the cost price of the first quality of tea or the mixing ratio.
   • Combined: Using both statements together, we have all necessary information (cost prices of both qualities and the mixing ratio) to calculate the selling price.

3. Final Answer: Both statements together are sufficient, but neither statement alone is sufficient.

Correct Option: C

Would you like further clarification or detailed calculations? Here are five questions to expand understanding:

1. How is the weighted average formula derived for mixtures?
2. What happens if the ratio changes? How does it affect the cost price of the mixture?
3. Can we calculate profit margins using this approach if a selling price is given?
4. What are some common applications of this mixture method in real-world scenarios?
5. How can you generalize this formula for $n$-quality mixtures?

Tip: Always verify whether the ratio and all costs are available before attempting a mixture problem.