Video Transcript
Given that a submarine is descending below the sea level at a rate of 60 feet per minute, determine the depth at which the submarine will be after 10 minutes.
So we have a submarine that is descending. So it is going down deeper into the sea, and it is going at a rate of 60 feet per minute. So we can do this a couple of ways. We can say that after one minute, it went down 60 feet. So after another minute, that would be two minutes that went by, we went down another 60 feet, which would be 120.
After another minute, we’d be down to 180 feet. After another minute, we’d be down another 60 feet, which would be down to 240 feet. After five minutes, we’d be down 300 feet. And after repeating this process, by the time we got to 10 minutes, the submarine will have descended 600 feet, which would be our final answer.
Another way that we could do this: if we knew that we were descending 60 feet per minute and we knew that each minute we were dropping 60 feet, how many would it be after 10 minutes? We could simply replace the minutes with 10, and 60 feet times 10 would give us 600 feet.
So given that a submarine is descending below the sea level at a rate of 60 feet per minute, the depth at which the submarine will be after 10 minutes would be 600 feet.
