X, Y and Z can do a piece of work in 46 days, 92 days and 23 days, respectively, X started the work. Y joined him after 2 days. If Z joined them after 8 days from the beginning then for how many days did X work?
A boat covers 12 km upstream & 18 km downstream in 3 hrs, while it covers 36 km upstream & 24 km downstream in 6.5 hrs. What is the speed of the current?
Pipes A and B can fill a tank in 4 hours and 6 hours 40 minutes, respectively; whereas a third pipe C can empty the full tank in 1 hours 40 minutes. A and B are opened at 2:00p.m. and 3:00 p.m., respectively and C is opened at 4:00 p.m. The tank will be completely empty at: