Question 524120
2m^3 @ 35% sand = .35*2 = .7 m^3 of sand
6m^3 @ 15% sand = .15*6 = .9 m^3 of sand
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So we have 8 m^3 of soil containing 1.6 m^3 of sand.
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1.6/8 * 100 = 20% sand by volume
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Done.