Zach works at the Verizon store and wonders if iPhones last longer if the screen brightness is set to low. He selects a random sample of 20 brand new iPhones from this store and
randomly splits them into two groups of 10. For the first group of 10 iPhones, he sets the
screen brightness to low and then starts a movie. For the second group of 10 iPhones, he
sets the screen brightness to high and then starts a movie. For each iPhone, he measures
the amount of time until the battery is all the way dead. He finds that the low brightness
iPhones lasted longer, on average, than the high brightness iPhones.
(a) Was this an observational study or an experiment? Explain your reasoning.

(b) What is the explanatory variable and the response variable?

(c) Was a random sample used to collect the data?
(d) Was random assignment used to set up an experiment?
(e) What conclusion can we make from this study?

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”

light-year  

the distance that light travels in a vacuum in one year, equal to about 9.46 trillion km (5.88 trillion mi). light-years are used in measuring interstellar and intergalactic distances.  

parsec  

a unit of distance used in astronomy, equal to about 3.25 light years (3.08 × 1016 meters).  

parallax  

the apparent angular displacement of a celestial body due to its being observed from the surface instead of from the center of the earth (diurnal parallax or geocentric parallax) or due to its being observed from the earth instead of from the sun (annual parallax or heliocentric parallax)  

absolute magnitude  

the magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs.  

apparent magnitude  

the magnitude of a celestial object as it is actually measured from the earth.  

redshift  

an increase in the wavelength of radiation emitted by a celestial body as a consequence of the doppler effect.  

the great thing about your imagination is that it doesn't have to make sense! if i were you i would be stuck in space, no communication with earth travelling around and around, you can only guess how long its been since your communication broke down. you land on an undiscovered planet, you do a scientific investigation examining the elements and conditions. you come across alien lifeforms.  

best of luck!