Question 852415
A winery has a vat with 2 pipes leading to it.
 The inlet pipe can fill the vat in 7 hours while the outlet pipe can empty in 10 hours.
How long will it take to fill the vat if both pipes are left open?
:
let t = time to fill the vat when both valves are open
let the completed job = 1 (a full vat)
:
fill is plus, empty is minus
:
{{{t/7}}} - {{{t/10}}} = 1
multiply by 70, cancel the denominators and you have
10t - 7t = 70
3t = 70
t = 70/3
t = 23{{{1/3}}} hrs to fill the vat
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