Question

A person has to select one of three capsules. one capsule makes his weight increase by 1 kg, another one ensures weight doesn't change. the third one makes him gain 2kg n also compels him to select one of three capsules once again - all similar to d first set of 3 capsules. the person has no way of identifying d capsules beforehand and is equally likely to take any of d three capsules at any stage. find d expected gain in weight.