10. The time between calls to a plumbing supply business is exponentially distributed with a mean time between calls of 15 minutes. a. What is the probability that there are no calls within a 30-...

Extracted text: 10. The time between calls to a plumbing supply business is exponentially distributed with a mean time between calls of 15 minutes. a. What is the probability that there are no calls within a 30- minute interval? b. What is the probability that at least one call arrives within a 10-minute interval? c. What is the probability that the first call arrives within 5 and 10 minutes after opening? d. Determine the length of an interval of time such that the probability of at least one call in the interval is 0.90