<PRE><B>Question 619780</B>
    using a particular hose take 4 hours to fill a tank. When a second hose is used, both hoses can fill the tank in 1 hrs. how long would it take to fil the tank using only the second hose
.
Let x = time (hours) it takes 2nd hose to fill tank alone
then
1(1/4 + 1/x) = 1
(1/4 + 1/x) = 1
multiplying both sides by 4x:
(x + 4) = 4x
4 = 3x
4/3 hours = x
or
1 and 1/3 hours = x
or
1 hour and 20 minutes = x
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