you are interested in determining which of two brands of batteries, brand A and brand B, lasts longer under differing conditions of use. One hundred fenix flashlights are fitted with brand A batteries and 100 olight flashlights are fitted with brand B batteries. each battery is used for 72 hours straight. The battery life is then measured for each battery, adn the average battery life for the two brands is comprared. what is wrong with this experimental design