From 6 different novels and 3 different dictionaries, 4 novels and 1 dictionary are to be selected and arranged in a row on a shelf so that the dictionary is always in the middle. The number of such arrangements is :
(1) at least 1000
(2) less than 500
(3) at least 500 but less than 750
(4) at least 750 but less than 1000
