The time allotted is 4 hours or 240 minutes. If you divide
240 by 2 (pretending like there’s only one photographer), then you get
the number of slots there are for students to be photographed. If
there are 120 slots and 600 students, divide 120/600 to get 1/5 of the
students who would be photographed with 1 photographer. In order
to take every student’s picture, 5 photographers would be needed.
(D)