Commonly used IE approaches to solve this problem are heuristics, simulation, queuing theory and optimization. Most approaches consider either direct waiting costs or indirect waiting costs, but not both. Solution 1 - In this method, a single batch process is followed in which a certain block of session is allocated to the doctor and the available session duration is divided into intervals, and most of the patients are served before the end of the session. The major disadvantage of this system is that the length of the interval is not constant. The number of patients is the decision variable. Appointments are made at FIFO. It can be classified into single block calendar and sequential block calendar. Solution-2 It uses queuing theory and was generally considered to be a unitary process. In this approach, appointments are scheduled at fixed regular intervals, the duration of the interval is a decision variable, and the hours of service are a random variable. Cost-based optimizations are used to reduce waiting costs and most of the waiting times in this method are direct waits.