John & Mary’s Anniversary

Alice and Bob want to know the date of John and Mary’s anniversary. John gives them the list of possible dates below. January 4th, 5th, or 8th February 6th or 7th March 3rd or 5th April 3rd, 4th or 6th Mary then tells Alice only the month and tells Bob only the day. Alice says: I don’t know when their anniversary is but I know that Bob doesn’t either. Bob says: I didn’t know when their anniversary was but now I do. Alice says: Now I also know when their anniversary is. When is John and Mary’s anniversary?

Alice and Bob want to know the date of John and Mary’s anniversary. John gives them the list of possible dates below.

• January 4th, 5th, or 8th

• February 6th or 7th

• March 3rd or 5th

• April 3rd, 4th or 6th

Mary then tells Alice only the month and tells Bob only the day.

Alice says: I don’t know when their anniversary is but I know that Bob doesn’t either.

Bob says: I didn’t know when their anniversary was but now I do.

Alice says: Now I also know when their anniversary is.

When is John and Mary’s anniversary?