<PRE><B>Question 131491</B>
66 kilograms of cement is mixed with 22.5 kilograms of water. However, the mixture is supposed to be 40% water in order to dry properly. Find the amount that should be added. 
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Start: 22.5/66 = 34% water in the cement before additional water added
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Add:  x kg of water
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End up with: (x+66) kg of cement containing 40% water.
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EQUATION:
water + water = water
22.5 + x = 0.40(66+x)
22.5 + x = 26.4 + 0.4x
0.6x = 3.9
x = 6.5 kg of water must be added
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Cheers,
Stan H.</PRE>