There are two plants that a civil engineer can purchase the required concrete for a high-rise building
construction. Each truckload of concrete produced at plant A is defective, i.e. not fulfilling the standard
requirements, with probability of 5%, whereas each one produced at factory B is defective with
probability of 1%. Suppose that the civil engineer purchased two truckloads of concrete that were
produced at the same factory, which is equally likely to have been either factory A or factory B. If the
first truckload of concrete is defective, what is the conditional probability that the other one is also
defective?
