565 kg to the nearest 5 kg means that the total weight of the people on
board, W, could be represented as
562.5 < W < 567.5
But Fred's weight, F, could be represented as
87.5 < F < 88.5
Let's assume the lower bound for Fred....this makes the elevator as heavy as possible
So....when he gets out of the elevator......the greatest possible total weight will now be less than
567.5 - 87.5 = 480 kg
So...it is safe to ride