Jack usually mowes his lawn in 7 hours. Marilyn can mow the same yard in 4 hours. How musch time would it take for them to mow the lawn together?
3 hrs
jack mows (1/7) lawn per hour
marilyn mows (1/4) yard per hour
together they mow 1/7 + 1/4 yard per hour
= 4/28 + 7/28 = 11/28 yards per hour
so
28/11 = about 2.54 hours/yard
Which one is the answer? 3 or 2.54?
Damon's answer is correct.
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".
Let's first figure out the work rate of each person. Work rate is often measured in "units per hour". So, if Jack mows the entire lawn in 7 hours, his work rate would be 1/7 of the lawn per hour. Similarly, if Marilyn mows the same lawn in 4 hours, her work rate would be 1/4 of the lawn per hour.
Now, to find out how much time it would take for them to mow the lawn together, we need to add up their work rates. So, Jack's work rate is 1/7 of the lawn per hour, and Marilyn's work rate is 1/4 of the lawn per hour. Together, their work rate would be 1/7 + 1/4 of the lawn per hour.
To combine these fractions, we need a common denominator, which in this case is 28. So, Jack's work rate can be written as 4/28 and Marilyn's work rate can be written as 7/28. Adding them together gives us a combined work rate of 4/28 + 7/28 = 11/28 of the lawn per hour.
Now, we know that their combined work rate is 11/28 of the lawn per hour. To find out how much time it would take for them to mow the entire lawn together, we can set up a simple equation:
(11/28) * t = 1
Here, 't' represents the time it would take for them to mow the lawn together, and 1 represents the entire lawn (since they want to mow it completely).
To solve for 't', we can multiply both sides of the equation by 28/11:
t = (28/11) * 1
Now, we can simplify:
t = 28/11
Therefore, it would take them approximately 2.55 hours (or about 2 hours and 33 minutes) to mow the lawn together.