Explanation:

- Let's analyze the mixture: 3 parts of rice at Rs.45 per kg and 2 parts of another rate.

- Use the weighted average method:

- The cost of the first type of rice is Rs.45.

- The cost of the mixture is Rs.50.

- Calculate the rate of the second quality using the formula:

- \((3 \times 45) + (2 \times x) = 5 \times 50\)

- Simplifying the equation: \(135 + 2x = 250\)

- Solving for \(x\): \(2x = 115\) or \(x = 57.5\)

- Options:

1. Rs.57 is not correct

2. Rs.57.5 is correct

3. Rs.58 is not correct

4. Rs.58.5 is not correct

- Correct Answer: Rs.57.5