Jack usually mows his lawn in 4 hours. Marilyn can mow the same yard in 7 hours. How much time could it take for them to mow the lawn together?
2 6/11 hrs
To find out how much time it would take for Jack and Marilyn to mow the lawn together, we can use the concept of work rates.
First, let's calculate their individual work rates. Jack can mow the lawn in 4 hours, so his work rate is 1 lawn / 4 hours, which can also be expressed as 1/4 lawns per hour. Similarly, Marilyn can mow the lawn in 7 hours, so her work rate is 1 lawn / 7 hours, or 1/7 lawns per hour.
To determine their combined work rate, we add their individual rates. So, the combined work rate of Jack and Marilyn is 1/4 + 1/7 lawns per hour, which can be simplified to (7 + 4) / (4 * 7) = 11/28 lawns per hour.
Now, to find the time it would take for them to mow the lawn together, we can divide the total work (1 lawn) by their combined work rate (11/28 lawns per hour):
Time = Total work / Combined work rate
Time = 1 / (11/28)
Time = 1 * (28/11)
Time = 28/11
Time ≈ 2.54 hours
Therefore, it would take approximately 2.54 hours for Jack and Marilyn to mow the lawn together.