The average weight of all the vehicles in a parking is 4000 kg. The average weight of 12 vehicles is 6000 kg. Average weight of the remaining vehicles is 3000 kg. Whatis the total numberof vehicles in the parking?

Let the total number of vehicles in the parking be x.
Then, Total weight of all vehicles = 4000x kg
Given, Average weight of 12 vehicles = 6000 kg
Total weight of 12 vehicles = 72000 kg
Remaining vehicles = x-12
Given, Average weight of (x-12) vehicles = 3000 kg
Total weight of (x-12) vehicles = 3000*(x-12) = 3000x-36000 kg
Then, 72000 + 3000x - 36000 = 4000x
=> 1000x = 36000 => x = 36
Therefore, Number of vehicles in the parking = 36.