Problem 1 -

An undergraduate business student has purchased a laptop computer for use during exams. This laptop is perfectly reliable except for two parts: its microchip, which has a failure rate of one in every 15 hours of operation; and its battery, which has a failure rate of one in every 20 hours of operation. Assuming that a new battery has just been installed, what is the probability that the LAPTOP will perform reliably during a 3 hour exam?

Problem 2 -

An undergraduate business student has purchased a laptop computer for use during exams. This laptop is perfectly reliable except for two parts: its microchip, which has a failure rate of one in every 30 hours of operation; and its battery, which has a failure rate of one in every 40 hours of operation. Assuming that a new battery has just been installed and the student brings one spare, fully charged battery with him, what is the probability that the LAPTOP will perform reliably during a 2 hour exam?

Problem 3 -

An undergraduate business student has purchased a laptop computer for use during the upcoming semester. This laptop is very reliable, but she is concerned that the battery will wear out before the end of the semester. According to the Manufacturer, on average the battery will wear out in 140 hours, with a standard deviation of 6 hours. After looking at her course schedule, she anticipates 146 hours of time will be needed working on the laptop. What is the probability that the battery will last this amount of time or longer?