In a cellular phone system, a mobile phone must be paged to receive a phone call. However, paging attempts don’t always succeed because the mobile phone may not receive the paging signal clearly. Consequently, the system will page a phone up to three times before giving up. If the results of all paging attempts are independent and a single paging attempt succeeds with probability 0.8, sketch a probability tree for this experiment and find the probability P[F] that the phone receives the paging signal clearly.