Mixture S is 20% oil and 80% material B by weight. If 2 more kilograms of oil are added to the 8 kilograms mixture S, how many kilograms of mixture S must be added to make a 70% material B in the new mixture?  Answers.
A) A)6	B) B)7	C) C)8	D) D)9	E) E)10
Can be done with weighted avg method.   if 2 kg more of oil is added to 20% oil of 8 kg mix,then a 10kg of mix will have 3.6kg (or 36%) of oil .   S1=20(initial mix.)   Avg. is what we need..ie 70% of material B means 30% of oil   S2=36(36% of 10 kg mix)   w1/w2=(S2-Avg)/(Avg-S1)   (36-30)/(30-20)   6/10   means for every 10 kg of new mix. we need 6 kg of mix S   6ns 6
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Mixture S is 20% oil and 80% material B by weight. If 2 more kilograms of oil are added to the 8 kilograms mixture S, how many kilograms of mixture S must be added to make a 70% material B in the new mixture?