little bit of maths into our boring lives

MartinM57 sed:

Say tractor A takes A hours to do the field
Say tractor B takes B hours to do the field

In 1 hour, tractor A does 1/A of the field
In 1 hour, tractor B does 1/B of the field

The field was done by 10 hours-worth of tractor A and 4 hours-worth of tractor B

So ...
10/A of the whole hours to do the field by tractor A +
4/B of the whole hours to do the field by tractor B =
the whole hours to do the field

If the whole hours to do the field = X, then

(10/A * X) + (4/B * X) = X

Divide throughought by X

10/A + 4/B = 1

...but B = A - 3

So
10/A + 4/(A-3) = 1

which can be solved for A (via a quadratic equation - I'll leave you to do that!)

...and B = A-3, leading to B


Do I get the Christmas mince pie?

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Optikon said:

Tractor A (slow one) can do it by himself in 22 Hours.
Tractor B (3 times faster) by himself would take 7 hours 20 minutes.

:lol: :lol: :lol:

Sounds like my yard! So whats the answer?

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bloody-orc said:

A tractor works 6h on a field. other tractor sees it and comes to help. together thew work for 4h and then the task is done. how many hours will it take for each of those tractors to do the task on theyr own (from the beginning to the end) if second tractor will do the task 3hours faster than the first tractor.

what do you get for the answer. plz give the way you got the answer aswell.

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panic mode said:

Optikon,

how is that? slow tractor can do it in 8 hrs alone and fast tractor in just 5hr when they both have been in field for 10hrs working together?
what if slow tractor can do it in 15 hours and fast in 12?

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bloody-orc said:

the answer cant be less than 10 h for rhe slow tractor so all the answers you have told are incorrect. martins is correct: it gives 15 and 12.

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A tractor works 6h on a field. other tractor sees it and comes to help. together they work for 4h and then the task is done.

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