Mixture W is 20% oil and 80% material B by weight. If 2 more kilograms of oil are added to the 8 kilograms mixture W, how many kilograms of mixture W must be added to make a 70% material B in the new mixture?
Select the correct option: 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 .   W1=20(initial mix.)   Avg. is what we need..ie 70% of material B means 30% of oil   W2=36(36% of 10 kg mix)   w1/w2=(W2-Avg)/(Avg-W1)   (36-30)/(30-20)   6/10   means for every 10 kg of new mix. we need 6 kg of mix W   6ns 6
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Mixture W is 20% oil and 80% material B by weight. If 2 more kilograms of oil are added to the 8 kilograms mixture W, how many kilograms of mixture W must be added to make a 70% material B in the new mixture?