Jack usually mows his lawn in 3 hours. Marilyn can mow the same yard in 5 hours. How long would it take them to mow the lawn together?
Jack's rate alone = 1/3
Marilyn's rate = 1/5
combined rate = 1/3 + 1/5 = 8/15
time at combined rate = 1/(8/15) = 15/8 = 1.875 hrs
or 1 hour and appr 53 minutes
4 hours
To find out how long it would take Jack and Marilyn to mow the lawn together, we can use the concept of rates.
Jack's rate of mowing the lawn can be expressed as 1 lawn per 3 hours, or 1/3 lawns per hour. Similarly, Marilyn's rate of mowing the lawn is 1 lawn per 5 hours, or 1/5 lawns per hour.
To determine their combined rate, we can add up their individual rates:
1/3 + 1/5 = 8/15 lawns per hour.
This means that together, Jack and Marilyn can mow 8/15 of a lawn per hour.
To find out how long it would take them to mow the entire lawn, we can divide the total lawn by the combined rate:
1 lawn / (8/15 lawns per hour) = 15/8 hours.
So, it would take Jack and Marilyn together 15/8 hours, which is equivalent to 1 hour and 52.5 minutes, to mow the lawn.