Hypothetical Statistics Question Regarding Class Curve, Standard Dev, and Mean

#1
Theoretical question:

So say there is a course where if you score two standard deviations below the mean, you will fail the course. The class average will be roughly a 75%, not sure what to set as the baseline for standard dev, and say 150 people are in the class. One person is added to the class now who knows all of the material really well and will get a 100% on every exam. Will the addition of this student cause the failing score (two standard deviations below the mean) to be higher because there is now a higher mean, or lower because the standard deviation will increase. Not sure how to approach this problem, would love some insight.