Discussion:
Q: The Manager at a light bulb factory wants to determine whether there is any difference in the mean life expectancy of light bulbs manufactured on two different, whether there is any difference in the mean life expectancy of light bulbs manufactured on two different models of machines. The population standard deviation of machine 1 is 110 hours and of machine 2 is 125 hours. A random sample of 25 light bulbs from machine 1 indicates a sample mean of 375 hours, and a similar sample of 25 from machine 2 indicates a sample mean of 362 hours.
a. Using the 0.05 level significance, is there any evidence of a difference in the mean life of bulbs produced by the two types of machines?
b. Compute the p-value in (a) and interpret its meaning.