Thirty six vehicles are parked in a parking lot in a single row. After the first car, there is one scooter. After the second car, there are two scooters. After the third car, there are three scooters and so on. Work out the number of scooters in the second half of the row.
Let C and S denote car and scooter respectively.
Then, the sequence of parking is
C S C S S C S S S C S S S S C S S S|S S C S S S S S S C S S S S S S S C
The above sequence has been divided into two equal halves by a line.
Clearly, numbers of scooters in second hlaf of the row = 15.