describe the probability using exponential distribution.
The Johnson family utilizes a propane tank for cooking on their gas grill. During the summer they want to replace their tank on average every 30 days.
At a arbitrarily chosen moment and what is the probability that they can grill out
(a) At least 40 days before they want to replace their tank? (Round your answer to 4 decimal places.)
(b) No-more than 20 days? (Round your answer to 4 decimal places.)