A Researcher Is Interested in the Relationship Between the Walkability $\pm$

A researcher is interested in the relationship between the walkability of various cities (defined as how easy it is for residents to walk places as opposed to driving)and obesity rates for residents of these cities.An index is created to measure walkability which can range from 1-7,and 20 major cities in the United States are measured.For each city obesity rates per 1000 people were obtained.Data are in the table below,as well as the rankings for each variable,and difference scores.

SD² = 2350
a.Calculate the Spearman correlation coefficient for the above data set.
b.What are the degrees of freedom for this example.
c.Convert the Spearman correlation coefficient to a t score.
d.Using a critical value of $\pm$ 2.101,describe the statistical conclusion regarding the null hypothesis,and describe the strength and nature of the relationship.