Alex drank 16 glasses of water, each glass containing $\frac{1}{8}$litres. How many litres of water did he drink?

1. 2 litres
2. 4 litres
3. 1.5 litres
4. 2.5 litres

A glass holds 200 millilitres of water. How many glasses are required to fill a water bottle of 1 litre. (1 litres = 1000 ml)

If a glass holds $\frac{1}{4}$ litres of water, how many glasses of water is required to fill a bottle whose capacity is $\frac{5}{2}$ litres?