Half of the students in a calss are girls.if the number of boys was twice as large and the number of girls half as large
问题描述：
Half of the students in a calss are girls.if the number of boys was twice as large and the number of girls half as large,what would the percentage of boys in the calss become?
答
80%
现在男女数量一样.设 # boys = # girls = x.
如果男孩数量翻倍,那么#boys= 2*x=2x
女孩数量减半,那么#girls=0.5*x = 0.5x
男孩percentage（百分比）就是2/(2+0.5)*100% = 2/2.5*100%=80%