ACT Quiz 15 - Sequences and Sums

The difference between consecutive numbers below is the same. What are the two missing numbers? 21, ____, ____, 48

• 27, 34

• 28, 32

• 29, 37

• 30, 39

• 31, 38

• 8

• 90

• 100

• 110

• 120

• 130

What is the 5th term in this sequence of "square" numbers, defined by the figures below: 1, 4, 9, ...?

• 8

• 21

• 23

• 25

• 27

• 8

• 10

• 12

• 14

• 16

One can build a chain of equilateral triangles out of matchsticks as shown below. How many matchsticks are needed to construct a chain of 30 triangles?

• 33

• 60

• 61

• 75

• 90

Which of the following statements is NOT true about the arithmetic sequence shown below?

19, 15, 11, 7, 3, ...?

• The sixth term is -1

• The sum of the first four terms is 52

• The seventh term is -5

• The common difference of consecutive terms is -4

• The common ratio of consective terms is -4

The third term of an arithmetic sequence is 18, and the fourth term is 9. What is the second term? (Note: In an arithmetic sequence, consecutive terms differ by the same amount.)

• -9

• 0

• 9/2

• 27

• 36

What is the 6th term of the geometric sequence 1, -3, 9, -27, ...?

• -243

• -81

• 81

• 243

• 729

In the geometric sequence below, the 1st term is 2. If it can be determined, what is the 7th term?

2, -6, 18, -54, 162, ...?

• -1,458

• -486

• 486

• 1,458

• Cannot be determined