Chapter 1

a. lower bone density among 70-year-olds than among 35-year-olds . b. faster recall of lists of words by 20-year-olds than by 60-year-olds *c. higher percentage of blue-collar workers among 50-year-olds than among 30-year-olds . d. a lower rate of marital satisfaction among couples in their 30s than among couples in their 50s . 1-4. ................
................