Percentage Errors in Equipment used in an experiment.?

In a titration experiment we used a 250 cm3 conical flask with +/- o.5cm3 error; a 25cm3 pipette with +/- 0.05cm3 error and aa 50cm3 burette with a +/- 0.15cm3 error. I have worked these out to 0.2;0.2 and 0.3 cm3 respectively. Have I calculated the maximum percentage error correctly? If not , where did I go wrong? Also how do i estimate the overall apparatus maximum error. I think you total them which would give in my calculations +/- 0.7% ? Your help is appreciated all you out there!