任务型阅读 阅读下面的短文，根据短文内容完成相关任务。
There is a family of ants close to my house, but I don't know when they came here.
They work hard all day long cleaning their house and looking for food outside. There is not a lazy one in their family. They are friendly to each other and help each other. I like them very much and often go to see them.
One day I went to see the ants just before a heavy rain. They were busy carrying earth in their mouths to stop up the door of their house. Just then the rain came down. I ran back into the house. I thought,“The ants will be in danger. How heavy the rain is!”
When the rain stopped, I went out to see the ants. The earth at the door kept the rain out. They were busy carrying it away.
It was late, and the people all went home. I thought that the ants must be tired.I went to see them again with the help of the lamp. They were still working quietly. What good, hard-working neighbours they are!
小题1:Who is the writer's neighbour?
小题2:What did they do all day long?
小题3:They aren't very kind to each other, are they?
小题4:What did they use to keep the rain out?
小题5:Do they go to sleep just as the people do in the evening?
要求：(1)计算两个方案的投资回收期； (2)计算两个方案的平均报酬率； (3)根据上述计算结果，比较两个方案的优劣。 (计算结果保留小数点后两位)