Mathematics

Question

An electrician can wire a house in 20 hours. if she works with an apprentice, the same job can be completed in 12 hours. how long would it take the apprentice, working alone, to wire the house?

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1 Answer

  • we know that
    An electrician can wire a house in ------------> 20 hours
    so
    100%----------------> 20 hours
     X-------------------> 12 hour
    x=12*100/20----> x=60%

    that means 
    the apprentice in 12 hours complete the (100-60)----> 40%

    the apprentice in 12 hours complete -------> 40%
    x hours------------------------------------> 100%
    x=100*12/40-----> x=30 hours

    the answer is
    30 hours