有一道GRE的数学题求详细讲解：
问题描述：
有一道GRE的数学题求详细讲解：
RT
The advertisd rate for roaming harges is 0.002 cents pe second.What is that in dollars per hour?
0.072
答
就直接进行单位换算就好啦,1 dollar=100 cents,1 hour=3600 second
0.002 cents pe second=0.002/100*3600=0.072 dollars per hour