Question

A contractor estimates that 3 persons could rewire Jasminder's house in 4 days. If, he uses 4 persons instead of three, how long should they take to complete the job?

Answer 1

Let the number of days required by 4 persons to complete the job be x.
The following table is obtained.

Number of days	4	x
Number of persons	3	4

If the number of persons is more, then it will take lesser time to complete the job.
Hence, the number of days and the number of persons required to complete the job are inversely proportional to each other.
Therefore, $4 × 3 = x × 4$
$x = \frac{4 × 3}{4}$
Thus, the number of days required to complete the job is 3.