A student is preparing to take a standardized exam. She was told that she needs to get plenty of sleep the night before the exam. She is interested in the relationship between the number of hours of sleep a student gets before the exam and the score earned on the exam. She collects information from 10 other students who have already taken the exam as shown in the table.She fits a least-squares regression line to the data and determines the equation of the line is ŷ =26 – 0.18x, where ŷ is the score earned on the exam and x is the number of hours of sleep the night before the exam. The residual plot is given.