$$R^{2} = r^{2} = 0.8^{2} = 0.64$$ 
\textbf{The height and age of each child in a random sample of children was recorded. The value of the correlation coefficient between height and age for the children in the sample was 0.8. Based on the least-squares regression line created from the data to predict the height of a child based on age, which of the following is a correct statement?} 

1. \textbf{~On average, the height of a child is 80\% of the age of the child.} 
2. \textbf{The least-squares regression line of height versus age will have a slope of 0.8.} 
3. \textbf{The proportion of the variation in height that is explained by a regression on age is 0.64.~} 
4. \textbf{The least-squares regression line will correctly predict height based on age 80\% of the time.} 
5. \textbf{The least-squares regression line will correctly predict height based on age 64\% of the time.} 