A diver is 7ft above water. The diver descends 12 ft in total. How deep is he in the water?

Answer 1

5 feet

We have a diver standing 7 feet above the water, who then descends 12 feet. How deep in the water is the diver?

Let's think about it this way: first our diver drops 7 feet from whatever perch s/he is on to land on the water. So we've gone down 7 out of our 12 or we can say:

#12-7#, which is to say we have 12 feet to go down and have already gone down 7. How many more feet do we have to go down until we stop?

#12-7=5# feet more. And so the diver is 5 feet under the water.

We can also think of the surface of the water as #0# and any distance above the water as positive and any distance under the water as negative. So we start at #+7# or in other words seven feet above the water, and end up at #-5# or in other words five feet under the water. And we can express this in math terms like this:

#7-12=-5# or we start at 7 feet above the water, move 12 feet towards the water (also known as "down") and end up 5 feet below the water.

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Answer 2

Gabriel Agustin

The diver is 19 feet deep in the water.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.