the algorithm for the von-neumann acceptance-rejectiom method is as follows:
1. generate a random number u
between 0 and 180 (from the x-axis)
2. generate a random number v
between 0 and 7 such that 0<u<7 (since it must be greater than the maximum frequency distribution).
3. if v<f(u), accept number u, else reject
4. go back to step 1.
The random number generated in step 1 must follow the probability of occurance as per the distribution in the image on the fist post, for example, the probability of mean service being 1 = 1/17, probability of mean service being 2 = 3/17 etc.