Question

6 tractors take 7 days to collect the harvest. How long would it take 15 tractors to do the same amount of work?

Answer 1

`2.9166666666` days

Explanation:

Assuming that each tractor does the same amount of work toward the total each day and that adding tractors does not diminish the amount of work done for the additional tractors (each tractor, regardless of how many continue to work independently at the same rate), we proceed.

It took `7` days for `6` tractors to do `100%` of the job.

7 days / 6 tractors `(7/6)` days per tractor.

Divide `7/6` by `6` to find the amount of work each tractor can do each day.

`7/6 / 6 = 7 / 36` using the reciprocal multiplication rule.

So, `7/36 = x/ 15`.

Solve for `x` using cross multiplication.
`36x = 105`

`x = 105 / 36`

`x = 2.9166666666` days.

Just a little less than `3` days.