Basic Ability Number Series and Sequences Questions and Answers

Question 1

What is the next number in the following sequence: 3, 7, 15, 31, 63, ...?

Accepted Answer

127

Answer

The pattern in this sequence is to multiply the previous number by 2 and then add 1. For example, (3 * 2) + 1 = 7, and (7 * 2) + 1 = 15. Following this pattern, the next number is (63 * 2) + 1 = 127.

Question 2

A warehouse employee is stacking boxes in a pyramid shape. The top layer has 1 box, the second layer has 4 boxes, the third has 9, and the fourth has 16. If this pattern continues, how many boxes will be in the seventh layer?

Accepted Answer

49

Answer

The number of boxes in each layer corresponds to the square of the layer number. Layer 1 has 1^2 = 1 box, Layer 2 has 2^2 = 4 boxes, Layer 3 has 3^2 = 9 boxes, and so on. Therefore, the seventh layer will have 7^2 = 49 boxes.

Question 3

Identify the missing number in the sequence: 5, 6, 8, 11, ?, 20.

Accepted Answer

15

Answer

This is an arithmetic sequence where the difference between consecutive terms increases by 1 each time. The differences are +1, +2, +3, +4, +5. So, 5+1=6, 6+2=8, 8+3=11, 11+4=15, and 15+5=20. The missing number is 15.

Question 4

Which of the following sequences is a geometric progression?

Accepted Answer

81, 27, 9, 3, 1

Answer

A geometric progression is a sequence where each term after the first is found by multiplying the previous one by a fixed, non-zero number called the common ratio. In the sequence 81, 27, 9, 3, 1, each term is found by dividing the previous term by 3 (or multiplying by 1/3).

Question 5

Find the next two numbers in the interleaved sequence: 10, 30, 12, 25, 14, 20, ?, ?

Accepted Answer

16, 15

Answer

This is an interleaved or twin sequence. The first sequence (10, 12, 14, ...) increases by 2. The second sequence (30, 25, 20, ...) decreases by 5. Therefore, the next number in the first sequence is 14 + 2 = 16, and the next number in the second sequence is 20 - 5 = 15.

Basic Ability Test Practice Test

Basic Ability Test Practice Test

Basic Ability Number Series and Sequences Questions and Answers