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

To solve this problem, we can use the concept of "person-days," which represents the total work done by a number of workers over a certain number of days.

Step 1: Calculate the total work in person-days
The contractor estimates that 3 persons can rewire the house in 4 days. So, the total work in person-days is:

Total work = 3 persons * 4 days = 12 person-days.

Step 2: Determine the number of days required with 4 persons
Now, if 4 persons are doing the same amount of work, the number of days required can be calculated by dividing the total work (12 person-days) by the number of workers (4 persons):

Number of days = Total work / Number of persons Number of days = 12 person-days / 4 persons = 3 days.

Final Answer:
If 4 people are used, it will take them 3 days to complete the job.