MAT Exam 2020 Paper

Concept:Assume a common total volume for each vessel equal to the LCM of the sum of ratio parts, then add the petrol and kerosene amounts separately.Explanation:The ratios in the three vessels are $4:1$, $5:2$, and $6:1$.Total parts in each vessel are $5$, $7$, and $7$.LCM of $5,7,7$ is $35$. Take the total volume of each vessel as $35$ litres.First vessel: petrol $=4 \times \frac{35}{5}=28$, kerosene $=1 \times \frac{35}{5}=7$.Second vessel: petrol $=5 \times \frac{35}{7}=25$, kerosene $=2 \times \frac{35}{7}=10$.Third vessel: petrol $=6 \times \frac{35}{7}=30$, kerosene $=1 \times \frac{35}{7}=5$.Total petrol $=28+25+30=83$.Total kerosene $=7+10+5=22$.Thus, the ratio of petrol to kerosene in the final mixture is $83:22$.Answer:$83:22$, i.e. option B.