<PRE><B>Question 730475</B>
 One pump can fill a water cistern twice as fast as a second pump.
 Working together, the two pumps can fill the cistern in 5 hours.
 Find how long it takes each pump to fill the cistern when working alone
:
Let t = time required by one pump alone
then
2t = time required by the other pump
:
Let the completed job = 1 (a full cistern)
:
A typical shared work equation
Each will do a fraction of the work, the two fractions = 1
{{{5/t}}} + {{{5/(2t)}}} = 1 
multiply by 2t, resulting in
2(5) + 5 = 2t
10 + 5 = 2t
t = 15/2
t = 7.5 hrs for one pump
you can find the time for the other pump</PRE>