3 The ratio of boys to girls at the dance was 10 to 15. How many girls were at the dance if there were 60 boys at the dance? Answer

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”?