Tea worth Rs. 126 per kg and Rs. 135 per kg are mixed with a third variety in the ratio 1 : 1 : 2. If the mixture is worth Rs. 153 per kg, the price of the third variety per kg will be:

Tea worth Rs. 126 per kg and Rs. 135 per kg are mixed with a third variety in the ratio 1 : 1 : 2. If the mixture is worth Rs. 153 per kg, the price of the third variety per kg will be: Correct Answer Rs. 175.50

Since first and second varieties are mixed in equal proportions.
So, their average price
$$\eqalign{ & = {\text{Rs}}{\text{.}}\,\,\left( {\frac{{126 + 135}}{2}} \right) \cr & = {\text{Rs}}{\text{.}}\,\,130.50 \cr} $$
So, the mixture is formed by mixing two varieties, one at Rs. 130.50 per kg and the other at say, Rs. x per kg in the ratio 2 : 2, i.e., 1 : 1. We have to find x.
By the rule of alligation, we have:

$$\eqalign{ & \therefore \frac{{x - 153}}{{22.50}} = 1 \cr & \Rightarrow x - 153 = 22.50 \cr & \Rightarrow x = 175.50 \cr} $$