The following table shows the rate of live births in the U.S. for the years 1976, 1986, and 1996. The rates shown are per 1000 women per age-group. For example, in 1986 the live-birth rate was 30.5 for women aged 15-17. This means that for every 1000 women in this age group, 30.5 had a pregnancy that ended with a live birth.

1. Draw three separate bar graphs (one for each year) depicting the data in the table above.
2. For each of the three years, approximate the mean age at which women gave birth and the corresponding standard deviation. Explain your reasoning and show all work. (Hint: Referring to the 1996 data, you could estimate these by saying 34 16-year-olds gave birth, 86 18¹/₂-year-olds gave birth, 110 22-year-olds gave birth, etc.)
3. Discuss your results from Problem 2. Are the mean ages significantly different? Is the spread of data significantly different? Did you expect this? Why or why not?
4. Suppose that in 1996 the ages of women who gave birth were normally distributed with mean 25.4 and standard deviation 6.5. (How close is this to your estimate?)
   1. About what percentage of women who gave birth were older than 30?
   2. About what percentage of women who gave birth were between 18 and 22?
   3. About what percentage of women who gave birth were younger than 20 or older than 40?
5. In 1996 an estimated 6.240 million pregnancies resulted in 3.891 million live births, 1.366 million induced abortions, and 0.983 million fetal losses.
   1. What percentage of pregnancies ended in fetal loss?
   2. Based on the 1996 data, about how many abortions will occur for every 100 pregnancies?
   3. Use your result from Problem 4a to estimate the number of women 30 years or older that gave birth in 1996.