Question

136 vehicle 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.

• A. 61
• B. 62
• C. 63
• D. 64
• E. None of the above

Answer 1

The correct option is C 63

Number of vehicles in the second half $=\frac{136}{2}=68$
Arrangement of cars and scooters = 2 + 3 + 4 + 5 + ... + 16 + 1 = 136
2 + 3 + 4 + 5 + ... + 11 + 3 = 68
9 + 13 + 14 = 15 + 16 + 1 = 68
The number of scooters in the second half of the row
= 9 + 12 + 13 + 14 + 15 = 63
Hence, the required answer is 63.