physics GRE-astronomy/optical help-stat help

[lifes3ps]

really lost, dont know what to solve for.

2 stars are separated by an angle of 3*10^(-5). whats diameter of smallest telescope that can resolve the two stars using visible light (600nm)? ignore atmospheric interference

(2.5cm)

2. student makes 10 1second measurements of the disintegration of a sample of a long lived radioactive isotope and obtains the following values:
3,0,2,1,2,4,1,2,5

how long should person count to establish an uncertainty of 1 percent?

i hardly know what theyre asking for here. half life?