Question 38573
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One garden hose can fill an above-ground in 10 hours. A second 
hose can fill the pool twice as fast as the first one. If both 
hoses are used together to fill the pool, how many hours will 
it take?

Let x = the number of hours it takes if both hoses are used

>>...One garden hose can fill an above-ground pool in 10 hours...<<

Therefore in 1 hour the first hose can fill 1/10th of the pool

Therefore, in x hours the first hose can fill x/10ths of the pool  

>>...A second hose can fill the pool twice as fast as the first one...<<

This tells us that the second hose can fill it in only 5 hours, since
the first one can fill it in 10 hours.

Therefore in 1 hour the second hose can fill 1/5th of the pool

Therefore, in x hours the first can fill x/5ths of the pool 

To get the equation:

(Fraction of pool the 1st hose fills in x hours) +
             (Fraction of pool the 1st hose fills in x hours) =
                            One pool filled in x hours

   x/10 + x/5 = 1
          
Can you solve that? If not post again
Hint: clear of fractions by multiplying thru by LCD = 10

Answer: 3 1/3 hours or 3 hours 20 minutes.

Edwin
AnlytcPhil@aol.com</pre>