Chapter 2 - Section 2.4 - Average Rate of Change of a Function - 2.4 Exercises - Page 189: 34

Year 1982, 500 books Year 1985, 620 books Year 1990, 820 books Year 1992, 900 books Year 1995, 1020 books Year 1997, 1100 books Year 1998, 1140 books Year 1999, 1180 books

For the year 1982, it has only passed 1 year since 1981, so 40 new books were added. Adding those new books and the old ones in 1981 (which were 460) equals 500. For the year 1985, it has passed 4 years since 1981, so 160 new books were added (4 years x 40 books per year =160 books). Adding those new books and the old ones in 1981 (which were 460) equals 620. For the year 1990, it has passed 9 years since 1981, so 360 new books were added (9 years x 40 books per year = 360 books). Adding those new books and the old ones in 1981 (which were 460) equals 820. For the year 1992, it has passed 11 years since 1981, so 440 new books were added (11 years x 40 books per year =440 books). Adding those new books and the old ones in 1981 (which were 460) equals 900. For the year 1995, it has passed 14 years since 1981, so 560 new books were added (14 years x 40 books per year =560 books). Adding those new books and the old ones in 1981 (which were 460) equals 1020. For the year 1997, it has passed 16 years since 1981, so 640 new books were added (16 years x 40 books per year =640 books). Adding those new books and the old ones in 1981 (which were 460) equals 1100. For the year 1998, it has only 1 year since 1997, so 40 new books were added. Adding those new books and the old ones in 1997 (which were 1100) equals 1140. For the year 1999, it has only 1 year since 1998, so 40 new books were added. Adding those new books and the old ones in 1998 (which were 1140) equals 1180.