Bag 1 contains 4 white and 6 black balls while another Bag 2 contains 4 white and 3 black balls. One ball is drawn at random from one of the bags and it is found to be black. Find the probability that it was drawn from Bag 1.

The Bayes' theorem describes the probability of an event based on prior knowledge of the conditions that might be relevant to the event. The theorem is named after English statistician, Thomas Bayes, who discovered the formula in 1763.