A car is parked among N cars standing in a row, but not at either end. On his return, the owner finds that exactly 'r' of the N places are still occupied. The probability that the places neighbouring his car are empty is

A car is parked among N cars standing in a row, but not at either end. On his return, the owner finds that exactly ‘r’ of the N places are still occupied. The probability that the places neighbouring his car are empty is

Question : A car is parked among N cars standing in a row, but not at either end. On his return, the owner finds that exactly ‘r’ of the N places are still occupied. The probability that the places neighbouring his car are empty is