Riddle

How can you measure nine minutes with have two hourglasses, one four minute and one seven minute?

Choose an answer

A.Just run the seven-minute timer twice
B.Add four and seven minutes for nine minutes total
C.Use only the four-minute timer three times
D.Turn over both hourglasses; when the four-minute runs out, flip it; when seven-minute runs out, flip it; when four-minute runs out again, flip seven-minute; nine minutes total
Hint: It's a 27-word phrase with 138 letters, starting with "T".

Answer

Turn over both hourglasses; when the four-minute runs out, flip it; when seven-minute runs out, flip it; when four-minute runs out again, flip seven-minute; nine minutes total

Why this is the answer

Track the moments each timer runs out and flip the appropriate one to build up to nine minutes.

This riddle is filed under Time, Money, Music Riddles and rated Hard.