how much sand do you need to add to 10ft to the third powerof soil with 22% sand in order to make a soil with 35% sand?
10 ft³ of soil with 22% sand contains
S = 10[ft³]*0.22 = 2.2 ft³
of sand. In order to make a soil with 35% sand we need to add M ft³ of sand that must satisfy following condition:
(10+M)*0.35 = M
3.5 + 0.35M = M
3.5 = 0.65M
M = 3.5/0.65 ft³ = 70/13 ft³.
So, we need to add 70/13 ft³ of sand.
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