# Thread: Rational Equation to solve work problem.

1. ## Rational Equation to solve work problem.

One group of construction workers can build a skyscraper in 240 days. Another group of construction workers can build the same skyscraper in 180 days. How long will it take them to build three of these same skyscrapers if the two groups work together?

No clue how to work out the above. TIA!

2. Originally Posted by eagertolearn
One group of construction workers can build a skyscraper in 240 days. Another group of construction workers can build the same skyscraper in 180 days. How long will it take them to build three of these same skyscrapers if the two groups work together?

No clue how to work out the above. TIA!
Work done by group 1 in a day = (1/240)th portion of the work
Work done by group 2 in a day = (1/180)th portion of the work

Now if they work together, the work done by both the group will be added,
i.e. total work done in 1 day by both group = [(1/240) + (1/180)] part of the work.
= [(3+4)/720] = (7/720)th part of work.

time required to complete the work = 720/7 days = 102.86 day.

well, that was the complete solution!

3. Hello everyone
Originally Posted by annran
Work done by group 1 in a day = (1/240)th portion of the work
Work done by group 2 in a day = (1/180)th portion of the work

Now if they work together, the work done by both the group will be added,
i.e. total work done in 1 day by both group = [(1/240) + (1/180)] part of the work.
= [(3+4)/720] = (7/720)th part of work.

time required to complete the work = 720/7 days = 102.86 day.

well, that was the complete solution!
Don't forget to multiply this answer by 3, since three skyscrapers were required!