Answer (Choose 1 answer)
An electrical firm manufactures light bulbs that have a length of life that is approximately normally distributed with a standard deviation of 40 hours. If a sample of 30 bulbs has an average life of 780 hours, find a 96% confidence interval for the population mean of all bulbs produced by this firm.
Let 20.04 1.751, 20.02 = 2.054 10.02.29 2.15, 10.04.29 = 1.814
A. [665, 955]
B. None of the other choices is correct
C. [765, 795]
Back Next D. [865, 895]
Ε. [775, 785]
