<PRE><B>Question 508410</B>
a tank is filled with 2 pipes. the first pipe can fill the tank in 10 hours.
 But after it has been opened for 3 1/3 hours, the second pipe is opened and the tank is filled up in 4 hours more. 
how long would it take the second pipe to fill the tank?
 the two pipes have different diameters.
:
from the given information we know that the 1st pipe was open for 7 1/3 hrs.
Convert that to {{{22/7}}} hrs
:
let  p = the time required by the 2nd pipe to fill the tank
let a full tank = 1
:
A typical mixture equation
{{{(22/7)/10}}} + {{{4/p}}} = 1
which is
{{{22/70}}} + {{{4/p}}} = 1
Multiply by 70p to clear the denominators
22p + 4(70) = 70p
280 = 70p - 22p
280 = 48p
p = {{{280/48}}}
p = 5.83 hrs or 5 hrs 50 minutes



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