Answer: Cramming One Thursday, researchers gave students

Chapter 9, Problem 12RE

(choose chapter or problem)

One Thursday, researchers gave students enrolled in a section of basic Spanish a set of 50 new vocabulary words to memorize. On Friday, the students took a vocabulary test. When they returned to class the following Monday, they were retested—without advance warning. Here are the test scores for the 25 students.

\(\begin{array}{|c|c|c|c|c|c|c|} \hline \text { Fri. } & \text { Mon. } & \text { Fri. } & \text { Mon. } & \text { Fri. } & \text { Mon. } \\ \hline 42 & 36 & 48 & 37 & 39 & 41 \\ 44 & 44 & 43 & 41 & 46 & 32 \\ 45 & 46 & 45 & 32 & 37 & 36 \\ 48 & 38 & 47 & 44 & 40 & 31 \\ 44 & 40 & 50 & 47 & 41 & 32 \\ 43 & 38 & 34 & 34 & 48 & 39 \\ 41 & 37 & 38 & 31 & 37 & 31 \\ 35 & 31 & 43 & 40 & 36 & 41 \\ 43 & 32 & & & & \\ \hline \end{array}\)

a) What is the correlation between Friday and Monday scores?

b) What does a scatter plot show about the association between the scores?

c) What does it mean for a student to have a positive residual?

d) What would you predict about a student whose Friday score was one standard deviation below average?

e) Write the equation of the regression line.

f) Predict the Monday score of a student who earned a 40 on Friday.