英文国三数学~~英文和数学的请进~~an alloy wieghing 400g is made up of 80% copper by wieght. If 100g copper is added to the alloy,what will be the percentage change in tha proportion of copper by wieght in the alloy?(请包括步骤~~如有需要,我可以翻译一下问题(但我太懒了~~
2019-06-14
英文国三数学~~英文和数学的请进~~
an alloy wieghing 400g is made up of 80% copper by wieght. If 100g copper is added to the alloy,what will be the percentage change in tha proportion of copper by wieght in the alloy?(请包括步骤~~如有需要,我可以翻译一下问题(但我太懒了~~
优质解答
The original weight of copper = 400x80% = 320g
The percentage of copper in the new alloy = 420/500 x100 = 84%
The new weight of copper in the alloy = 400gx84% = 336g
The % change= (336-320)/320 x 100 =5%
The original weight of copper = 400x80% = 320g
The percentage of copper in the new alloy = 420/500 x100 = 84%
The new weight of copper in the alloy = 400gx84% = 336g
The % change= (336-320)/320 x 100 =5%