Free help with homework

Why join Brainly?

  • ask questions about your assignment
  • get answers with explanations
  • find similar questions


When the 4-minute one runs out, turn it over immediately so it starts counting 4-minutes again

When the 7-minute one runs out, turn it over so it starts counting again

The moment the 4-minute one runs out for the second time, turn the 7-minute hourglass over - it will have only been running exactly one minute. 

Let the sand run back again (1 minute more) and then straight away, 9 minutes. 

(4 minutes twice, plus one more minute = 9 minutes!)
0 0 0
The Brain
  • The Brain
  • Helper
Not sure about the answer?
Learn more with Brainly!
Having trouble with your homework?
Get free help!
  • 80% of questions are answered in under 10 minutes
  • Answers come with explanations, so that you can learn
  • Answer quality is ensured by our experts