Q3.

In a mixture of 50 liters, milk and water are in the ratio 3 ∶ 2. How much of water should be added to make ratio equal?

Q4.

Simplify the following expression∶

\(\left( {\frac{2}{3} \times \frac{1}{6}} \right) + \left( {\frac{2}{3}\; \times \;\frac{7}{2}} \right) - \left( {\frac{{13}}{4} \times \frac{4}{3}} \right)\; = \;?\)

Q5.

Two pipes A and B can fill an empty cistern in 4.8 and 7.2 hours, respectively. Pipe C can drain the entire cistern in 9.6 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 16.8 hours to fill the cistern. For how many hours was Pipe B turned on?