A bus shuttles between two neigbouring towns every two hours. It starts from 8 AM in the morning and the last trip is at 6 PM. On one day the driver observed that the first trip had 30 passengers and each subsequent trip had one passenger less than the previous trip. How many passengers travelled on that day?
Since the bus starts at 8 a.m. and the last trip is at 6 p.m. and it takes two hours for one trip, the total number of trips is 4.
Number of passenger in first trip = 30
∴Total number of passengers = 30 + 29 + 28 + 27 + 26 = 140