Researchers studied the relationship between how long a person uses a computer before bed and how long a person sleeps each night. People were selected at random to participate in the study. The computer use of each participant was classified as minimal, moderate, or extreme. The relative frequency table below summarizes the results of this study. There were 17 people in the study who were both moderate computer users and got 5 to 7 hours of sleep. How many people in this study were both extreme computer users and got 5 to 7 hours of sleep?

Since moderate user got 5 to 7 hours of sleep, that means extreme users got less than 7 hours of sleep.

Hence no extreme user had 5 to 7 hours of sleep.

And mimimal users had greater than 7 hours of sleep.

a) one student is chosen from classroom a, then a student is chosen from classroom b.  

step-by-step explanation:

independent events are ones in which the probability of one event does not affect the probability of the second event.

one student is chosen from classroom a; this does not affect the chances of choosing a student from classroom b.   this makes these independent events.

when one card is chosen from a standard deck and then set aside before a second card is chosen, the probability of the second card being chosen changes.   this makes them dependent events.

when one student is chosen from classroom a and then a second student is chosen from classroom a, the probability of choosing the second student changes.   this makes them dependent events.

when a letter is chosen from the alphabet and then a second letter is chosen, the probability of choosing the second letter changes.   this makes them dependent events.