A research submarine descends 65 meters per minutes to a depth of 4485 m, conducts experiments, and then ascends at a rate of 65 meters per minute to the surface. The submarine carries 12 hours worth of oxygen. How much time does the crew have to conducts experiments?

Step-by-step explanation:

speed = 65m/mins = 65/60 = 1.083m/s

Time taken to go down,

t = 4485/1.083

= 4141.37 s

Total time gotten = 12 hrs = 12*60*60

= 43200s

Amount of time left to conduct experiment

= 43200-4141.37

= 39058.63s

= 39058.63/3600

= 10.85 hrs

The crew have to conducts experiments FIVE times.

Step-by-step explanation:

The submarine descends 65 meters per minutes to a depth of 4485 m.

This means it takes it 4485/65 = 69 minutes to descend to that depth.

As it ascends at a rate of 65 meters per minute to the surface, it also takes it the same amount of time (69 minutes).

The submarine carries 12 hours, or 12x60 = 720 minutes, worth of oxygen.

To be safe back to the surface, the number of times for descending must be equal to that for ascending.

The total number of descending or ascending times = round [ (720:69) : 2] = 5.