The mean lifetime of electric light bulbs produced by a company has in the past been 1120 hours with a standard deviation of 125 hours. A sample of 20 bulbs revealed a standard deviation in the lifetimes of 150 hours. Would you conclude that this is unusual? Explain.© BrainMass Inc. brainmass.com March 4, 2021, 6:07 pm ad1c9bdddf
This problem is a test of hypothesis comparing the variance (and standard deviation) of a new distribution with a known variance from another distribution. A step by step process is used, all formulas and calculations are shown and each step is explained.