A submarine that is already at 605 feet below sea level ascends (rises up) 475 feet before descending (sinking down) another 255 feet.

-350ft

Step-by-step explanation:

so basically 605 is negative and 255 is a negative then you add those two then it would be -860 then you subtract the positive 475 and that will equal -350

step-by-step explanation: yes

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.