GATE 2024 ES – Question 61
Food, paper and plastic waste have densities280,80,50 kg/m³. A mixture contains 70%,20%,10% by mass, respectively. Neglect compaction and find mixed density in kg/m³,to two decimals.
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Correct answer: 142.00 to 143.00
Explanation
Take1 kg total mass and add component volumes: $V=.7/280+.2/80+.1/50=.007$ m³. Hence $\rho=1/.007=142.857143$ kg/m³,rounded **142.86 kg/m³**. The keyed calculation interprets the printed composition percentages as mass fractions; arithmetic density averaging would instead correspond to volume fractions.