at the end 同 in the end

In the end = finally, after a long time.
At the end = at the point where something stops.

1. I normally get paid at the end (of a week). (This sentence is incomplete without the phrase in brackets, esp when you say “normally”)
2. The students had a party at the end. (say, at the end of the semester)
3. Two of the runners collapsed at the end. (say, at the end of the marathon)
4. To my surprise I was offered the job in the end.
5. Judy got more and more fed up with her job in the end.
6. I tried to learn German but I found it too difficult in the end.
7. We couldn't decide whether to go to the party or not in the end.

hkslot's answer is the best answer and it is a good reference.

1 . I normally get paid __at the end__

2 . The students had a party__at the end

3 . Two of the runners collapsed_____at the end

4 . To my surprise I was offered the job__in the end

5 . Judy got more and more fed up with her job at the end

6 . I tried to learn German but I found it too difficult___at the end

7 . We couldn't decide whether to go to the party or not_at the end_

1 . I normally get paid at the end.

2 . The students had a party at the end.

3 . Two of the runners collapsed at the end.

4 . To my surprise I was offered the job in the end.

5 . Judy got more and more fed up with her job in the end.

6 . I tried to learn German but I found it too difficult in the end.

7 . We couldn't decide whether to go to the party or not in the end.