2(A + B + C)'s1day'swork=(130+124+120)=15120=18∴(A + B + C)'s1day'swork=12×8=116WorkdonebyA,B,Cin10days=1016=58Remainingwork=(1−58)=38A's1day'swork=(116−124)=148Now,148workisdonebyAin1daySo,38workwillbedonebyAin(48×38)=18days
% Cistern is filled by 2nd pipe in one minute =
% cistern filled by 1st and 2nd pipes in one minute = 8.33%;
According to question, Cistern is totally filled by 2nd pipe in last 10 minute. That means 2nd pipe filled 33.3% of the cistern in last 10 minute and 66.66% of cistern is filled by 1st and 2nd pipe together in =
= 8 minutes;
Thus, after 8 minute, 1st pipe must be turned off.