Question 14

Explanation

We will use the concept of inverse proportion to solve this problem. The more workers there are, the shorter the time required, and vice versa.

Calculating Total Workload

The total project workload can be expressed in "man-days":

Calculating Time with New Workers

If the number of workers is reduced to 64, the time required ($t$) is:

We calculate the division result:

Since the work takes $62.5$ days, it means the work will be completed in the middle of the 63rd day. So, the time required to complete the project is 63 days.