Answer
There are $117,600$ different lock combinations.
Work Step by Step
It is necessary to select 3 numbers from 50 in the correct order. So, the order is important. It is a permutation of 3 numbers from a group of 50 numbers.
$_{50}P_3=\frac{50!}{(50-3)!}=\frac{50\times49\times48\times47!}{47!}=117,600$
