20-21. Four terms in a geometric sequence are . Find . a = 3, b = 2 b. a = 3, b = 2/3 c. a = 3, b = 3/2 d. a = 2, b = 3/2 22-23. The arithmetic mean between two numbers is 10 and their geometric mean is 8. Find the two numbers. a. 4 and 16 b. 12 and 8 c. 5 and 15 d. 10 and 10 24. The sequence 4, a, b, c, d, 19 is an arithmetic sequence. Find the value of c. a. 10 b. 11 c. 12 d. 13 25. A finite sequence has seven terms. If the first and last terms are 4 and 22, respectively, what is the common difference? a. 3 b. 4 c. 5 d. 6 26. Insert two geometric means between and 2. a. b. c. d. 27. Which arithmetic sequence has the greater sum? M = 3, 6, 9, …, 60 N = 2, 4, 6, …, 50 a. M c. they have the same sum b. N d. cannot be determined 28. Which of the two sequences below has the greater number of terms? P = 1, 2, 3, …, 41 Q = 2, 4, 6, …, 80 a. P c. They have the same number of terms b. Q d. Cannot be determined 29. How many two-digit numbers are there which are divisible by 7? a. 11 b. 12 c. 13 d. 14 30. Write the rule (general term) of the sequence 2, 4, 8, … a. b. c. d.