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An alloy of zinc and tin contains 37% zinc by weight. Find the weight of zinc which must be added to 400 kg of this alloy if the final percentage of zinc is to be 70. |
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Answer» Total weight of alloy `= 400 kg` Let we add `x` kg zinc to make its weight `70%` in the alloy. Then, total alloy `= 400+x` Total zinc after adding `x` kg` = 37**400/100+x` `:. (400+x)**70/100 = (37**4)+x` `=>2800+7x = 1480+10x` `=>3x = 1320=> x = 440kg` So, zinc of weight of `440` kg should be added to get the desired mixture. |
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