Probability Puzzle: The Quantum Fluctuation

Solve for the probability of the cat in the box:

There is a cat in the box. The box is either open or closed. The probability of the box being open is 0.5. If the box is open, the probability of the cat being in it is 0.8. If the box is closed, the probability of the cat being in it is 0.2. What is the probability that the cat is in the box?

Box Probability Paradox