chemistry
posted by bun on .
6.2(+_ 0.2)  4.1 (+_ 0.1 ) + ?
[6.2( +_ 0.2)  4.1(+_ 0.1)] : 9.43(+_0.05)
find absolut uncertainty and relative uncertainty.
PLEASE HELP:I solved them and got the exact absolute uncertainty like the answer key, but I didn't get right answer of relative unsertainty, my answer for both case 9.5 %, but the answer key is 11% for both , why?
this is my solution :
for problem 1:
relative uncertainty = [sqr(0.2^2 + 0.1^2)/2.1] *100 am I wrong?
Please help, thank you in advance.

You calculated wrong.
relatuncert= sqrt(.04+.01)/2.1=sqrt(.05)/2.1= .106 rouned to two sig figures will be 11 percent.