Saturday, August 30, 2014

time and work

two pipes running together can fill up a cistern in 40/13 mins. If one pipe takes 3 mins more than the other to fill the cistern, find the time in which each time would fill the cistern?


if one pipe fills the cistern in x mins, then the other fills in x + 3 mins
so, (1/x) + ( 1/(x + 3)) = 13/40
so, (2x + 3) 40 = 13 x (x + 3)
on solving, x = 5 mins.
so, the other pipe will fill in 8 mins

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