Lisa has collected data To find That the number of pages per book on a book shelf has normal distribution. What is the probability that a randomly selected book has fewer than 153 pages of the mean is 193 pages and the standard deviation is 20 pages? Use the empirical rule

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”?