Chapter 12 - Data Analysis and Probability - 12-7 Theoretical and Experimental Probability - Practice and Problem-Solving Exercises - Page 774: 41

$\frac{1}{4}$

P(event)=$\frac{numberoffavorableoutcomes}{numberofpossibleoutcomes}$ There are 20 differences from the stem and leaf plot so this is the number of possible outcomes. Out of the 20, five are more than 20 points:(23, 27, 72, 35, 45) so this is the number of favorable outcomes. So, the probability is: P(more than 20 points)=$\frac{5}{20}$ -simplify- P(more than 20 points)=$\frac{1}{4}$