11-31. A recent World Health Services poll revealed that x = 976 out of nX = 1900 African women had their first child before the age of 15 years, and y = 732 out of nY = 1850 Asian women had their first child before they were 15 years old. If pX and pY are the respective proportions of African and Asian women giving birth before age 15, find a 95% confidence interval for pX − pY.