Jack usually mows his lawn in 4 hours. Marilyn can mow the same in 5 hours. How much time would it take for them to mow the lawn together?
From the time it takes to do the complete joh, calculate the time it takes to do per hour. The resulting rate can then be added to find the time it takes for both of them.
1/(1/4+1/5)=1/(9/20)=20/9=2 2/9 hours.
the time t that it takes for a salesman to drive a certain distance d varies inversely as the average speed r . it takes the salesman 4.75 h to travel between two cities at 60 mi/h . how long would the drive take ?
To determine how much time it would take for Jack and Marilyn to mow the lawn together, we can use the concept of work done.
First, let's calculate the work rate for Jack. Since he mows the lawn in 4 hours, his work rate is 1/4 of the lawn per hour.
Next, let's calculate the work rate for Marilyn. Since she mows the lawn in 5 hours, her work rate is 1/5 of the lawn per hour.
To find the combined work rate when they work together, we add their individual work rates. So, the combined work rate is 1/4 + 1/5.
Adding the fractions, we get 5/20 + 4/20 = 9/20.
Therefore, when working together, Jack and Marilyn have a combined work rate of 9/20 of the lawn per hour.
To determine how much time it would take for them to mow the whole lawn together, we can use the formula:
Time = 1 / Combined Work Rate.
Plugging in the value of the combined work rate, we get:
Time = 1 / (9/20) = 20/9 ≈ 2.22 hours.
So, it would take Jack and Marilyn approximately 2.22 hours to mow the lawn together.