Average Speed of Answer Predictor

Hi All, i'm in need of an average speed of answer predictor please, preferably in excel format, so we on 69 seconds ASA month to date and we have taken 3120 calls, the calculator needs to be in day increments so when i input the next days details it will tell me how many calls i still need to take and at what ASA in order to reach my month ASA SLA of 30 seconds, your help would be greatly appreciated.