Theres three people. So each person needs to do one third (1/3) of the report.
The report is 4 pages long. So now calculate how much 1/3 of 4 is
= 1/3 * 4
= 4/3
= 1 1/3 pages
So each person needs to do one and a third pages.
And if you think about it it makes sense. three people EACH doing one page (1 +1 +1 = 3 pages) and a third of a page (1/3 + 1/3 +1/3 = 1 page) = 4 pages (3 pages + 1 page)