(2) Cost price of 1st type of coffee= ₹170 Cost price of 2nd type of coffee= ₹ 180 Cost price of 3rd type of coffee= ₹ 220 Mean price of the mixture = ` 200By the rule of alligation, Ratio of quantity of 1st type and 3rdtype = (220 – 200) : (200 – 170) =2 : 3 Ratio of quantity of 3rd type and2nd type = (200 – 180) : (220 –200) = 1 : 1 ∴ Required ratio = 2 : 1 : (3 + 1)= 2 : 1 : 4