The operating lifetime, expressed in days, of a machine used for coating, is modelled by a random variable $Y$ which follows the exponential distribution with mean equal to 500 days.
What is the probability, rounded to the nearest hundredth, that the operating lifetime of the machine is less than or equal to 300 days?
Answer a: 0.45 Answer b: 1 Answer c: 0.55 Answer d: We cannot answer because data is missing