A tower's stability have done extensive studies of its increasing tilt. Measurements of the lean of the tower over time provide much useful information. The following table gives measurements for the years 1975 to 1987. The variable "lean" represents the difference between where a point on the tower would be if the tower were straight and where it actually is. The data are coded as tenths of a millimeter in excess of 2.9 meters, so that the 1975 lean, which was 2.9647 meters, appears in the table as 647. Only the last two digits of the year were entered into the computer.

Year      75          76          77          78          79          80          81          82          83          84          85          86          87

Lean     647        649        661        672        679        694        701        704        719        723        730        747        763

(b) What is the equation of the least-squares line? (Round to three decimal places.)

y = -61.125 +  9.32  x I know my answer are incorrect

What percent of the variation in lean is explained by this line? (Round to one decimal place.) %

(c) Give a 99% confidence interval for the average rate of change (tenths of a millimeter per year) of the lean. (Round to two decimal places.)

8.23 , 10.28 I know my answer are incorrect