What does 我知道 and 应该的 mean in this dialogue? There's this dialogue here: (3:20) https://www.youtube.com/watch?v=yelfxueMlvc


  
  请问，洗手间在哪里？
  洗手间？在那边。在那里的右手边。
  哦，好。我知道。谢谢.
  不客气，应该的。
  


So... "我知道" certainly doesn't mean "I know" here. Because if he had known, he wouldn't have asked. So what's the meaning? And my second doubt is about "应该的". It's the first time I hear it and none of my dictionaries gives a translation which would make sense to me here. What is it?
In this context:

我知道 means 我現在知道了 (now I know)
应该的 means 人與人之間互相幫忙是应该的 (people helping people is obligatory)

The one asked for information said &quot;我(現在)知道(了)&quot; to confirm he has received the information. If he just said &quot;好，谢谢&quot; (good, thank you), the one who gave him the information could not be sure that the information he gave was successfully passed along.
After someone thanking you, saying 不客气(you're welcome) is a polite respond. And that should be enough.
Adding &quot;应该的&quot; (it is a right thing to do) is to show humbleness.
Implying: My action is not a grace I grant you, but an moral obligation between common folks, no need to be too grateful