What you’ll learn to do: Given a known standard deviation of two population means, conduct a hypothesis test and interpret the conclusion

When purchasing light bulbs you have two main options. Information about the mean lifetime of the bulbs is listed on the packaging. Is there a statistically significant difference in the mean lifetimes of the bulbs? Items that are manufactured by machines often are set to have a known standard deviation. If data was gathered from two independent random samples from these light bulbs, a test on two population means with known standard deviations could be conducted.