The probability that a randomly selected newborn is a boy is actually more than 1/2.The number of newborn boys for every 100 newborn girls is called the sex ratio at birth. The birth order of a first child is 1, the birth order of a second child is 2, and so on. The sex ratios at birth are shown in Table 28 for various birth orders.
Table 28 Birth Orders versus Sex ratios at Birth
Birth OrderSex Ratio at Birth
1…………………………105.8
2…………………………105.1
3…………………………104.8
4…………………………104.4
5…………………………104.0
6…………………………103.4
Let r be the sex ratio at birth for newborns whose birth order is n.
a. Construct a scatterplot.
b. Is there a linear association, a nonlinear association, or no association?
c. Compute r. On the basis of the scatterplot and r, determine the strength of the association.
d. Find the probability that a randomly selected firstborn is a boy.
e. China limits the number of babies a couple can have to one or two babies. Chinese parents tend to want to have boys rather than girls (Source: NBC News). The sex ratio at birth in China in 2010 was 120 (Source: United Nations). Give a possible reason why the sex ratio at birth might have been so high.