Lalit is taking the train to the Library. He tells Roshni the hour............When is Lalit’s train and how do you know?

Question

Lalit is taking the train to the Library. He tells Roshni the hour of his train’s departure and he tells Anu at which minute it leaves. He also tells them both that the train leaves between 0600 and 1000.

They consult the timetable and find the following services between those two time:
0632 0643 0650 0717 0746 0819 0832 0917 0919 0950

Roshni then says “I don’t know when Lalit’s train leaves but i am sure that neither does Anu”

Anu Replies “I didn’t know his train, but now i do”

Roshni responds “Now I do as well!”

When is Lalit’s train and how do you know?

Answer 1

0917

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Roshni knows the hour and sees multiple minute options for that hour, therefore thinks Anu also doesn't know.

• 0632 0643 (unique) 0650
• 0717 0746 (unique)
• 0819 0832
• 0917 0919 0950

Anu understands what Roshni thinks about and finds the answer- it must be an hour with most repeat minutes without a unique number. It excludes 6th, 7th and 8th hour. Anu had confused between 0717 & 0917 and figures out 0717 to be excluded as Roshni states he doesn't know the time.