23. Telephone calls from an office are monitored and found to have a mean duration of 452 s and a standard deviation of
Posted: Tue Apr 26, 2022 6:56 pm
23. Telephone calls from an office are monitored and found to have a mean duration of 452 s and a standard deviation of 123 s. Determine (a) the probability of the length of a call being between 300 s and 450 s. the proportion of calls likely to last for more than 700 s. (b) a a 24. Light bulbs, having a mean life of 2400 hours and standard deviation of 63 hours, are used for a consignment of 4000 bulbs. Determine the number of bulbs likely to have a life in excess of 2600 hours,