document.write( "Question 20229: I need this answer quickly please:
\n" ); document.write( "You have 2 hourglasses-a 4 min. hourglass and a 7 min. hourglass. You want to measure 9 min. How do you do it?
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Algebra.Com's Answer #9777 by wuwei96815(245) $\"\"$ $\"About$

You can put this solution on YOUR website!
Do you mean to measure 9 minutes as a continuous measurement? For instance, from 12:00 to 12:09. Or do you mean to measure 9 minutes in total? For instance, 3 + 3 + 3 without regard to continuity.\r
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\n" ); document.write( "\n" ); document.write( "I think that I have an answer for you.\r
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\n" ); document.write( "\n" ); document.write( "First, get both timers flowing at the same time. When the 4 minute timer runs out of sand, turn over both timers. When the 7 minute timer runs out of sand, turn over both timers again. At this point there should be 1 minute of sand left in the 4 minute timer. When that runs out, turn it over immediately (at this point you can disregard the 7 minute timer). When it runs out of sand again, turn it over for the last time. The last three runs of the 4 minute timer will add up to 9 minutes (1+4+4=9).\r
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\n" ); document.write( "\n" ); document.write( "I hope that is the right answer. \n" ); document.write( "

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