Explanation:(a) Was this an observational study or an experiment? Explain your reasoning. Experiment, because certain variables were controlled (he sets the screen brightness to low and then starts a movie) to determine if iPhones last longer if the screen brightness is set to low, and it proves the cause and effect relationship.
(b) What is the explanatory variable and the response variable? Response Variable- To determine if iPhones last longer if the screen brightness is set to low Explanatory variable- he sets the screen brightness of 10 of the iPhones to high and starts a movie, then the other 10 to low and starts a movie.
(c) Was a random sample used to collect the data? Yes- “he selects a random sample of 20 brand new iPhones”
