Problema Solution
Ivan hired 2 workers to mow his lawn. A worker can mow the lawn in 2 hours. Ivan on his own can finish the job in 4 hours. How long will it take to mow the lawn if they all work together?
Answer provided by our tutors
One worker can mow the lawn in 2 hours thus his rate is 1/2 lawns per hour.
Ivan on his own can finish the job in 4 hours thus his rate is 1/4 lawns per hour.
Let x = the number of hours the need to mow the lawn together and the together rate is 1/x lawns per hour.
The sum of the rates of the two workers (the both have the same rate) and Ivan's rate give the together rate:
1/2 + 1/2 + 1/4 = 1/x
by solving we find
x = 0.8 hr
x = 0.8*60 min
x = 48 min
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If they all work together they will mow the lawn in 48 minutes.