The following are the results of 20 lots. Each lot contains 750 objects. Number of defective objects in each lot are as follows:

48, 83, 70, 85, 90, 56, 51, 71, 36, 50, 29, 51, 29, 31, 37, 80, 70, 48, 67, 57. Analyze the data on the base of appropriate control chart. Calculate control limit and state whether the process is in control or not