Plz help guys everyone ignore me
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3382-299=3383- ? fill in the blank?

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?

If tan2a=cot(a+60), find the value of a, where 2a is an acute angle