An electronics gadget company has currently created the new line of fitness devices that monitor an individual's activity throughout the day. The lifetime of the device is distributed exponentially with an expected life time of 430 days. Once activated, the device is always on and is to be worn at all times.
State cumulative density function,
What is the probability that a randomly chosen device will have a lifetime greater than two years?
Suppose a group of 5 friends each purchase a new fitness device. What is the probability that 4 or more of the devices will have a lifetime greater than two years?