Percent error is found using the formula, |experimental value - actual value|/ actual value * 100 so first that would be |13.3-13.6|, which is .3 then .3/13.6, which is .022 finally .022*100, giving you an answer of about 2.20
So what I did was divide $50(Amount at the end) by 6 (the number of months). Which would give me the amount of money he made per month ($8.333...). So then $8.333.../$5000(Total $) is .166...% (Interest rate)