Out of three pipes the first two can fill an empty tank in 9 and 18 hours, respectively while the third can drain the filled tank in 15 hours. If all the three pipes are opened when the tank is empty, after how many hours will the tank be full?

Which of the following numbers is divisible by 9?

A force provides an acceleration of 0.5 $$m/sec^{2}$$ to a body of mass 2 kg. What acceleration will it produce when acting on a body of mass 10 kg ?

Read the given statement(s) and conclusions carefully and select which of the conclusions logically follow(s) from the statement(s).
Statement:
• All flowers are petals.
• All petals are soft.
Conclusions:
1. All flowers are soft.
2. Some soft are petals.

Two pipes A and B can fill an empty cistern in 1.8 and 2.7 hours, respectively. Pipe C can drain the entire cistern in 4.5 hours when no other pipe is in operation. Initially when the cistern was empty Pipe A and Pipe C were turned on. After a few hours Pipe A was turned off and Pipe B was turned on instantly. In all it took 5.5 hours to fill the cistern. For how many hours was Pipe B turned on?