document.write( "Question 601601: Alf can dig a trench in two hours, Bert takes three hours, Charlie takes 5 hours and Dave takes six hours. How long will they collectively take to dig the same trench if they all work simultaneously at their own speeds? \n" ); document.write( "

Algebra.Com's Answer #379894 by nerdybill(7384) $\"\"$ $\"About$

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Alf can dig a trench in two hours, Bert takes three hours, Charlie takes 5 hours and Dave takes six hours. How long will they collectively take to dig the same trench if they all work simultaneously at their own speeds?
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\n" ); document.write( "Let x = time (hours) it takes collectively
\n" ); document.write( "then
\n" ); document.write( "x(1/2 + 1/3 + 1/5 + 1/6) = 1
\n" ); document.write( "multiply both sides by common denominator 30:
\n" ); document.write( "x(15 + 10 + 6 + 5) = 30
\n" ); document.write( "x(36) = 30
\n" ); document.write( "x = 30/36
\n" ); document.write( "x = 0.8333 hours
\n" ); document.write( "or
\n" ); document.write( "x = 50 minutes
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