一道我总算不对的利率问题求教!!

The annual interest rate earned by an investment increased by 10 percent from last year to this year. If the annual interest rate earned by the investment this year was 1 percent, what was the annual interest rate last year?

这题我算的与答案始终有点差,不知是我错还是答案错了还是想请教下各位算出的是多少.为了不误导大家,我先不写出答案了.

去年 r1, 今年 r2 =1%, r2 = 110%* r1,

So, r1 = 0.909%，里面有什么 Trick 么？

答案是以下5个之一