Would you actually build a contingency chart for this question or is this just probability basics?
Bob sets two battery powered alarm clocks to make sure he wakes up in time for his 8 AM accounting test. Each alarm clock has a 25% failure rate (that is, there is a 25% chance he will sleep through the alarm). Assume the probability of him waking up for each alarm clock is independent. What is the probability that, using both alarms, he will oversleep