Solution:
average time that 3 lawn mowers operate = 930 min. on given day
total time they take for a day = average time per day x quantity of lawn mowers
this gives, 930 x 3 = 2790
minimum time that a lawn mower can operate = 900 min
hence, minimum two mowers can operate at 900 min then third mower will take time,
that will be ,2790 = ((2 x 900) + third mower time)
that will give , 990 min.
Hence, one of the mowers can operate for about 990 min.
