SAT SUBJECT TEST MATH LEVEL 2
PART 2
REVIEW OF MAJOR TOPICS
CHAPTER 3
Numbers and Operations
3.4 Sequences and Series
EXERCISES
1. If a1 = 3 and an = n + an–1, the sum of the first five terms is
(A) 17
(B) 30
(C) 42
(D) 45
(E) 68
2. If a1 = 5 and find a3.
(A) 2.623
(B) 2.635
(C) 2.673
(D) 2.799
(E) 3.323
3. If the repeating decimal is written as a fraction in lowest terms, the sum of the numerator and denominator is
(A) 16
(B) 47
(C) 245
(D) 334
(E) 1237
4. The first three terms of a geometric sequence are The fourth term is
(A)
(B)
(C)
(D)
(E)
5. By how much does the arithmetic mean between 1 and 25 exceed the positive geometric mean between 1 and 25?
(A) 5
(B) about 7.1
(C) 8
(D) 12.9
(E) 18
6. In a geometric series and . What is r ?
(A)
(B)
(C)
(D)
(E)
Answers and Explanations
1. (D) a2 = 5, a3 = 8, a4 = 12, a5 = 17. Therefore, S5 = 45
2. * (D) Press 5 ENTER into your graphing calculator. Then enter and press ENTER twice more to get a3.
3. * (C) The decimal = 0.2 + (0.037 + 0.00037 + 0.0000037 + · · ·), which is 0.2 + an infinite geometric series with a common ratio of 0.01.
The sum of the numerator and the denominator is 245.
4. (D) Terms are 31/4, 31/8, 1. Common ratio = 3–1/8. Therefore, the fourth term is 1 · 3–1/8 = 3–1/8 or
5. (C) Arithmetic mean Geometric mean The difference is 8.
6 (D) Therefore,