a The table shows the speed vs miles per hour for a certain

a) The table shows the speed vs miles per hour for a certain car model. Calculate the correlation coefficient r.

Xavg=25 Yavg=25

b) We are interested in knowing the combined correlation between miles per gallon and speed for the original car from part (a) and a new car. Miles per gallon for a new car is measured at four speeds and its average speed is 35mph with SD of 15mph and its average mpg is 40 with SD of 5. The correlation between speed and miles per gallon for the new car is .4.

Solution