A Large Company Buys Thousands of Lightbulbs Every Year

Essay

A large company buys thousands of lightbulbs every year. The company is currently considering four brands of lightbulbs to choose from and wants to investigate if the mean lifetimes of the 4 types of bulbs are the same. The research department randomly selected 7 bulbs of each type and test how long they lasted until they burned out. The research department then analyzed the data and obtained the following ANOVA table:

a) Fill in the blanks of the partially completed ANOVA table.
b) At test whether there are differences in the mean lifetimes of the four brands of lightbulbs.