GATE 2021 CE (CE2) – Question 63
An aggregate blend has coarse,fine,filler mass percentages 55,40,5 and bulk specific gravities 2.55,2.65,2.70. Find blend bulk specific gravity to two decimals.
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Correct answer: 2.58 to 2.61
Explanation
Blend volume is the sum of component volumes, so specific gravity is a mass-weighted harmonic mean: $G=1/(0.55/2.55+0.40/2.65+0.05/2.70)=2.596403$. Rounded, **2.60**. The arithmetic weighted mean would not preserve volume.