The distribution of the operating life for batteries produced by a manufacturer is approximately normal with standard deviation 3 hours. A random sample of 19 batteries has a mean operating life of 20 hours.
(a) Find a 90% conÖdence interval for the for the true mean life of the battery.
(b) Find the minimum number of batteries that should be sampled so that the length of the 90% conÖdence interval will not exceed 0.5.
Get Answers For Free
Most questions answered within 1 hours.