Answer to Math Olympiad #3

Problem:

A work crew of 3 people requires 3 weeks and 2 days to do a certain job.  How long would it take a work crew of 4 people to do the same job if each person of both crews works at the same rate as each of the others?  Note:  each week contains six work days.

Solution:

Each person of the work crew of three people worked 20 days.  Thus the number of individual work days needed to do the job was 60.  Then each member of the work crew of four people must work 15 days in order to provide a total of 60 individual work days.