Movie companies need to predict the gross receipts of individual movies once a movie has debuted. The following results, stored in are the first weekend gross, the U.S. gross, and the worldwide gross (in $millions) of the eight Harry Potter movies:

a. Compute the covariance between first weekend gross and U.S. gross, first weekend gross and worldwide gross, and U.S. gross and worldwide gross.
b. Compute the coefficient of correlation between first weekend gross and U.S. gross, first weekend gross and worldwide gross, and U.S. gross and worldwide gross.
c. Which do you think is more valuable in expressing the relationship between first weekend gross, U.S. gross, and worldwide gross-the covariance or the coefficient of correlation? Explain.
d. Based on (a) and (b), what conclusions can you reach about the relationship between first weekend gross, U.S. gross, and worldwide gross?