In a work problem, the number 1 represents the total amount of work. It is a true statement.
Because it is a general way of solving such problems.
For example, If a person take 5 hours to complete a job. This sentence implies that,the person do 1/5th portion of a work in 1 hour. So we divide the work into 5 portion, one portion is 1/5.
Therefore the total work is the sum of all portion of work, 1/5 + 1/5 +1/5 +1/5 +1/5 = 1
So In a work problem, the number 1 represents the total amount of work.