1. The problem statement, all variables and given/known data See image 2. Relevant equations n1sin(theta1) = n2sin(theta2) 1/s + 1/s' = 1/f 3. The attempt at a solution My question is for the second part. I think I've figured out why I got it wrong, but I'm not sure. So since the object distance (s) should be approximately 21 cm, then you apply the refraction theory to find s'=s*n1/n2 s'=21*(1.33) s'=~28 cm Is this correct?