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?
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
