Random Puzzles 

Workings

Hint
The last word is AGAIN.

Answer
Humpty Dumpty sat on a wall.
Humpty Dumpty had a great fall.
All the king's horses and all the king's men
Couldn't put Humpty together again.

Workings

Hint
Can the fractions be simplified?

Answer
667.

Reasoning
 3        8        1
———  of  ———  of  ———  of 2001
 4        9        2

which simplifies to:
24
——  of 2001
72

which simplifies to:
 1
———  of 2001
 3

Giving 667.

Workings

Hint
Fill the 9-litre container first.

Answer
Here are the contents of the containers after each stage:

A = 9 litres, B = 4 litres
A     B
9     0     fill A
5     4     fill B from A (leaving 5 litres in A)
5     0     empty B
1     4     fill B from A (leaving 1 litre in A)
1     0     empty B
0     1     fill B from A
9     1     fill A
6     4     fill B from A (only 3 more litres fit in B)
6     0     empty B

This leaves 6 litres in container A.

Workings

Answer
Gravity.