The correlation coefficient (r) between the number of volunteers x and the number of bags of trash collected y is 0.642.
What percent of the variation in the number of bags of trash collected can be
explained by differences in the number of volunteers? (Only state the number of the
percent in the answer blank, do not include the % in the answer blank, as the
computer already knows it is a percentage)

The students at jefferson middle school are raising money for a charity by selling t-shirts and hats. the number of t-shirts sold was 3 times the number of hats. the profit was $5 for each t-shirt sold and $2.50 for each hat sold. the students raised $840 for the charity. they used the system below to analyze their success and found the solution to be (144, 48). 5x+2.50y=840 x=3y how much did they earn from t-shirt sales?