# pre calc

posted by .

it takes my father 3 hours to plow our cornfield with his new tractor using the old tractor it takes me 5 hours. if we both plow for 1 hour before i go to school, how long will it take dad to finish the plowing.

I got 2.5 hours but i think that is totally wrong?????

• pre calc -

combined rate=field/3hrs + field/5hrs

time=field/(field/3 + field/5)
time= 15/(8)= less than your time.

## Similar Questions

1. ### math

If A farmer uses a large tractor,she can plow a filed in eight hours. Her sister, using a smaller tractor can plow the same field in 12 hrs. How many hours would it take to plow the field if they worked together ?
2. ### Physics

A tractor pulls forward a moving plow with a force of 2.5*10^4N, which is just large enough to overcome friction. A) what are the action, reaction forces between the tractor and the plow B) Are these reaction, action forces equal in …
3. ### Math

Joey can plow a field alone for in four hours. It takes Luigi five hours to plow the same field alone. If they work together, how long will it take them to plow the the field?
4. ### Math

School is out at 3:50 pm. Band practice is 2 1/2 hrs dinner takes 3/4 of an hour homework takes 1 1/4 hrs. You have to go to bed at 10. About how much time is left to play video games?
5. ### algebra 1

A farmer can plow a given field in 7 hours. If his son helps him, they can plow the field together in 4 hours. How long would it take his son to plow the field alone?
6. ### physics

You are driving your car along a country road at a speed of 21.5 m/s. As you come over the crest of a hill, you notice a farm tractor 35.7 m ahead of you on the road, moving in the same direction as you at a speed of 10.0 m/s. You …
7. ### math

if i plow at 7km/hr and my plow is 1800mm how long will it take to plow one ha
8. ### Math, algebra

A farmer buys a tractor for \$50,000. If the tractor depreciates 10% per year, find the value of the tractor in 7 years. Round to the nearest penny.
9. ### Math, algebra

A farmer buys a tractor for \$50,000. If the tractor depreciates 10% per year, find the value of the tractor in 7 years. Round to the nearest penny.
10. ### Algebra word problem

It takes john 12 hours to plow a field. After he had been working for 3 hours, his brother Mike came to help. Together they finished the job in 5 hours. How long would it take mike to plow the field working alone?

More Similar Questions