I was wondering if I could get help on this question I get lost after I use the formula to get 1.

Lisa has collected data to find that the number of pages per book on a book shelf has a normal distribution. What is the probability that a randomly selected book has fewer than170 pgs if the mean is190 pgss and the standard deviation is20 pgss? Use the empirical rule. Enter your answer as a percent rounded to two decimal places if necessary.