correct answer is: d) 24 days

Explanation

12 workers can fit a machine in 40 days
\therefore 1 workers can fit a machine in =\left(40\times12\right) days
\therefore 20 workers can fit a machine in =\large\left(\frac{40\times12}{20}\ \right) days
\rightarrow 24 days
Ans: 20 workers can fit the machine in 24 days.

These particular maths questions can also be asked in the following ways:

1. If 12 workers can install a machine in 40 days, how many days will it take for 20 workers to complete the installation?
2. How many days will it take 20 workers to install a machine if it typically takes 12 workers 40 days to do so?
3. If 12 workers can fit a machine in 40 days, how long will it take for 20 workers to complete the same task?
4. Suppose it takes 12 workers 40 days to fit a machine. How many days will it take for 20 workers to fit the same machine?