capegemini - two qualities of rice at rs63 per kg and rs6750 per kg are mixed with another quality of rice in the ratio 223 the final mixture sold at rs7650 per kg then the rate of third quality rice per kg was - skillgun

Given that, first and 2nd varieties are mixed in equal proportion.
Their average price = Rs.(63 + 67.50) / 2 = Rs.65.25
The new mixture is formed by mixing two varieties, one at Rs.65.25 per kg and the other at Rs.X per kg in the ratio 4:3. (note that, 2:2:3 becomes 4:3).
Given that, mean price of new mixture = Rs.76.50
We have to find X.
Applying the rule of alligation,Therefore, (Cheaper quantity) : (Dearer quantity) = (d - m) : (m - c) =
X - 76.50 / 11.25 = 4/3
3X – 229.50 = 45
X = 91.50
Hence, the required price of 3rd quality rice = Rs.91.50.