The fertility rate of a country is defined as the number of children a woman citi7en bears, on average, in her lifetime. Scientific American (Dec. 1993) reported on the declining fertility rate in developing countries. The researchers found that family planning can have a great effect on fertility rate. The table on page 514 gives the fertility rate, y, and contraceptive prevalence, x (measured as the percentage of married women who use contraception), for each of 27 developing countries. A SAS printout of the simple linear regression analysis is also provided on p. 504.

a. According to the researchers, "the data reveal that differences in contraceptive prevalence explain about 90% of the variation in fertility rates." Do you concur?

b. The researchers also concluded that "if contraceptive use increases by 15 percent, women bear, on average, one fewer child." Is this statement supported by the data'? Explain.