[EX03-045] Interstate 95, the longest of the north–south U.S. interstate highways, is 1907 miles long, stretching from Houlton, Maine, at the Canadian border on the northern end to Miami, Florida, at US 1 on the southern end. It travels across 15 east–coast states; the number of miles and the number of intersections in each of those states are listed here.

State FL GA SC NC VA MD DE Intersections 73 19 39 44 51 38 9 Miles 381 112 201 183 178 110 26 State PA NJ NY CT RI MA NH ME Intersections 16 28 12 68 26 44 4 52 Miles 58 44 29 118 47 97 17 306 Source: Rand McNally and http://www.ihoz.com/I90.html Using all 15 data:

a. Construct a scatter diagram with number of intersections as the dependent variable, y, and miles as the independent variable, x.

b. Does there seem to be a linear pattern to the data? Does the pattern seem reasonable for the variables? Explain why or why not.

c. Calculate the linear correlation coefficient, r.

d. Does the value of r seem reasonable compared with the pattern demonstrated on the scatter diagram? Explain.

Remove the CT (118, 68) from the data, then:

e. What is there about the Connecticut data point that makes it different? Is it understandable why it is different?

f. What effect did the removal of the Connecticut data point seem to have on the pattern?

g. Calculate the linear correlation coefficient, r.

h. What effect did the removal of the Connecticut point have on the value of r? How does this compare with the effect you anticipated? Explain.