How many kg of rice costing Rs. 42 per kg must be mixed with 30 kg of rice costing Rs. 54 per kg so that the mixture costs Rs. 50 per kg?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 15 kg
By the rule of alligation,
\(\text{cheaper} : \text{dearer} = (54 - 50) : (50 - 42)\)
\(= 4 : 8 = 1 : 2\)
So the cheaper rice is half the dearer rice:
\(\frac{1}{2} \times 30 = 15\) kg
Check: \(15 \times 42 + 30 \times 54 = 630 + 1620 = 2250\), and \(2250 \div 45 = 50\).