An urn contains five white and four black balls. Four balls are transferred to a second urn...© BrainMass Inc. brainmass.com September 24, 2018, 1:34 am ad1c9bdddf - https://brainmass.com/math/probability/probability-transfer-second-urn-205580
P(2nd ball white|1st ball black)=
P(2nd ball white and 1st black that are drew from 2nd urn| There is at least 1 white and 1 black in the second ...
This provides an example of finding probability after the objects have been moved.