Measure Nine Minutes


If you have two hourglasses -- one four-minute timer and one seven-minute timer, how can you measure nine minutes?


Turn over both hourglasses at once. When the four-minute hourglass runs out, turn it over. When the seven-minute hourglass runs out, turn it over. When the four-minute timer runs out this time (eight minutes have elapsed), the seven-minute hourglass has been running for one minute. Now turn over the seven minute timer back over. When the timer runs out, nine minutes have elapsed.

Rated 3/5 based on 88 votes
Measure nine minutes Riddle Meme.
Measure nine minutes Riddle Meme with riddle and answer page link.

Math Riddles

The Riddles Mission

The mission is to be the be the world's most comprehensive riddle website on the internet for riddles, puzzles, rebus caps and quizzes. Our riddle library contains interesting riddles and answers to test visitors and evoke deep thought and community discussion. Riddlers will benefit from the creativity of our members who participate in growth of our online riddles and puzzles resource. We encourage you to become a member of Riddles.