9.12.For nations listed in theHuman Development Report, the correlation with percentage of people using the Internet is 0.888 for per capita gross domestic product (GDP, a summary description of a nation's wealth), 0.818 for percentage using cell phones, 0.669 for literacy rate, 0.551 for fertility rate (the mean number of children per adult woman), and 0.680 for per capita emissions of carbon dioxide.

(a) Explain how to interpret the sign of the correlation between Internet use and (i) GDP, (ii) fertility rate.

(b) Which variable has the (i) strongest, (ii) weakest lin- ear association with Internet use?