Final answer:
To determine which batteries have a more uniform life in hours, compare the standard deviations of Duracell and Energizer batteries.
Step-by-step explanation:
In order to determine which batteries have a more uniform life in hours, we can compare the standard deviations of the life spans of Duracell and Energizer batteries. A lower standard deviation indicates a more uniform life span. If the standard deviation of Duracell batteries is lower than that of Energizer batteries, then Duracell batteries have a more uniform life.
To find the standard deviation, a study needs to be conducted on both Duracell and Energizer batteries. A sample of batteries from each brand should be randomly selected and their life spans should be recorded. The standard deviation of the life spans can then be calculated using a calculator or statistical software.