The cost of Type 1 rice is Rs. 15 per kg and Type 2 rice is Rs. 20 per kg. If both Type 1 and Type 2 are mixed in the ratio of 2 : 3, then the price per kg of the mixed variety of rice is:

Answer: Option A

Solution

Answer: Option A

Solution:

Let the price of the mixed variety be Rs. x per kg.
By rule of alligation, we have:

$$\begin{array}{rl}& \therefore \frac{20-x}{x-15}=\frac{2}{3}\\ & \Rightarrow 60-3x=2x-30\\ & \Rightarrow 5x=90\\ & \Rightarrow x=18\end{array}$$