Problema Solution
Carl can mow a lawn in 1 hour and 55 minutes. Doug can mow the same lawn in 2 hours and 40 minutes. How long will it take them to mow the lawn working together?
Answer provided by our tutors
the rate of Carl is 1/(11 + 55/60) lawns per hour
the rate of Dough is 1/(2 + 40/60) lawns per hour
let x = the number of hours they need to mow the lawn together.
the the together rate is 1/x lawns per hour
now we have
1/(11 + 55/60) + 1/(2 + 40/60) = 1/x
by solving we find
x = 2.18 hr
x = 1144/525
x = 1 hr 60*411/525 min
x = 1 hr 47 min
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together they will mow the lawn in 1 hr and 47 min.