Suppose you are taking an anti-insect ultrasound device powered by the battery type from Problem 3 on a 48-hour trip into the wilderness. Being cautious, you bring 3 batteries with you (1 in the flashlight and 2 spares). Assuming that failure times of batteries are independent, what is the probability that the device will be working throughout your trip? (HINT: In 48 hours, you expect to see on average 48/40=1.2 failures. Let X be a Poisson with lambda=1.2, denoting the average number of battery failures in your trip. You need to calculate P(X 3)=P(X=2).)