Will fan and medal! Can anybody check I did this right?

Question

anonymous · Answer

Investment                       Amount Invested            ROR
Certificate of Deposit       $6,800                            1.4%
US Treasury Bond             $9,300                           2.6%
Common Stock                 $10,335                         6.5%
Preferred Stock                 $5,053                           -2.3%

What is his weighted ROR? 

3.51%
2.00%
3.15%
2.77%

anonymous · Answer

This is the question and the possible answers, if anybody could show me how to get the weighted ROR I would be really grateful.

anonymous · Answer

I think the answer is 2.00% because if you set them up in order from least to greatest

-2.3%, 1.4%, 2.6%, 6.5%

The center is 1.4% and 2.6% so if I add them i get 4 and then divide it by 2 which is 2. Can anybody tell me if I did this right?