8. (20) Listed below are costs (in dollars) of air-fares for different airlines from New York City to San Francisco. The costs are base on tickets purchased 30 days in advance and on day in advance. 30 days x 240 250 254 284 288 328 290 One day y |556 514 587 843 728 988 536 a. Compute the correlation coefficient. b. Compute the slope of the linear regression line. c. Compute the y-intercept of the linear regression d. Use the equation of the regression line(and parts b. and c.) to give a point estimate of the cost of a ticket purchased one day in advance, given the ticket cost of $310 if purchased 30 days in advance of the flight. e. Give a 95% confidence interval for y when x is $310