A die is continuously rolled 65 -1 times. What is the probability that the total sum of all rolls does not exceed 225?

I know that the expected value for each roll is 7/2 so this means that the mean sum of all the rolls would be 64*(7/2) = 224.

Also, the variance for each roll is 35/12. How do I use this to find the std deviation in all the rolls?