1)

4 Men -> 1 field-> 7 days
4 Men ->1/7 field-> 1day
4 Men ->2/7 field->2 days
2 Men ->1/7 field->2 days
14 Men->1 field->2 days

2)
Tap A
2 minute->1 sink
1 minute->1/2 sink

Tap B
3 minutes->1 sink
1 minute->1/3 sink

Stopper
6 minutes->1 sink
1 minute->1/6 sink

1 minute->Tap A + Tap B - Stopper = 1/2 + 1/3 - 1/6= 4/6 sink
thus 1.5 min to fill the sink

3)
Pour water into the 5L container and from there pour water into the 3L container.

2L of water left in the 5L container. Pour away water in the 3L container and then pour the 2L of water into the 3L container.

Pour water into 5L container and from there pour water into the 3L container(there is already 2L of water in it)

When the 3L container is filled. 4L of water will be in the 5L container.