How do I write an equation that describes the situation?

Question

Michael is skin diving at a depth of 175 feet.When his oxygen tanks gets low he needs to head back to the surface.If it takes him 5 minutes to get to a depth of 50 feet.Write an equation that describes this situation.What was Michael's depth after 12 minutes?

Answer 1

The rate at which Michael ascends is found by taking

the number of feet he rose divided by the amount of

minutes it took him..   Michael ascended 125 ft in 5 mins

...(175-50 = 125) ... so his rate of ascension is 125/5 = 25 ft/min

 

Where D= depth, and m = # minutes rising

Michaels depth D can be calculated by

D = 175 - 25m  

 

After 12 minutes (m=12) Michaels' depth will be:

D = 175 - 25(12)

D = 175-300

D = -125

 

This basically means that had Michael continuously went upward

from the depth of 175 ft for 12 minutes he would end up 125 ft

above the water level....

 

This means that Michael has already reached the surface

before 12 minutes has elapsed.

 

Let's see how long it would take Michael to reach the surface

where depth is zero feet

 

0 = 175-25m

25m = 175

m = 7

 

Michael reaches the surface in 7 minutes from a depth

of 175 feet assuming a constant rate of ascension of 25 feet/minute

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Are you sure this wasn't supposed to say that he ascended
50 feet in 5 minutes?  That would give a rate of ascension
of 10 ft/minute and in 12 minutes he would go up 120 ft
so he would be at a depth of 175-120 = 55 ft