Answer: The movie was 3 hours and 17 minutes.
Step-by-step explanation: As it was already half an hour when the movie started it is likely to shorten the time passed 3 hours. If you carefully add up or even use a caculator as an example to help you add, you carefully put the numbers together in time version.
Thus, the asnwer is 3 hours and 17 minutes. (I hope this helps and that my explanation wasn't too confusing, this is just the way I do it.)