Question

If `6` tractors take `6` days to collect the harvest, then how many days will it take `18` tractors to collect the harvest?

Answer 1

2 days

Explanation:

Assuming they work at the same rate and are in direct proportion:
`6 = 6d`

Where `1` is multiplied, the other is divided. So to find out how long `1` worker takes, divide by `6` to get `1`, multiply by `6` to get `36d`.

`1 = 36d`

Now multiply `1` by `18`, divide `36d` by `18` to get `2d`:

`18 = 2d`

Answer 2

`2` days

Explanation:

This is an example of inverse proportion.

Where there are two quantities and one increases, the other will decrease. As there is a task to be completed (the harvesting), the MORE tractors that are doing the work, the LESS time it will take to do the job.

`x xx y =k`

For `6` tractors and `6` days: `k = 6xx6 =36`

If there are `3` times as many tractors, the job will be done in `1/3` of the time.

`x = 36/y`

`36/18 = 2` days