Question

5 kg of superior quality of sugar is mixed with 25 kg of inferior quality of sugar. The price of superior quality and inferior quality of sugar is Rs.18 and Rs.12 respectively. The average price per kg of the mixture is
(A) 13
(B) 15
(C) 18
(D) 21

Answer 1

Hint: Alligation- It is the rule that enables us to find the ratio in which two or more ingredients at the given price must be mixed to produce a mixture of the desired price.

Complete step-by-step answer:
Superior quality sugar quantity=5 kg
Price per kg of superior quality sugar= Rs.18 per kg
Total price of superior quality sugar= Rs. \[18 \times 5\]=Rs. 90
Inferior quality sugar quantity=25kg
Price per kg of inferior quality sugar= Rs.12 per kg
Total price of inferior quality sugar= Rs. \[12 \times 25\]=Rs. 300
After mixing 5 kg of superior quality with 25 kg of inferior quality we get,
Average price per kg of the mixture\[ = \dfrac{{300 + 90}}{{30}}\]=13Rs/kg.
Option (A) is correct.

Note: If the averages of two groups are separately given and the average of the whole group is given, then we can find out the ratio between the groups.