we know that
4 lb or less ------> is less than 20 lb ------> 120
5-9 lb------------> is less than 20 lb -------> 222
10-14 lb -------> is less than 20 lb ------->378
15-19 lb ------> is less than 20 lb-------> 256
Adds the number of passenger
120+222+378+256=976
therefore
the answer is 976