Test Index

SSC CPO SI and ASI Model Paper 4

Directions (Q. 7–9): What will come in place of the question mark (?) in the following number series?

Question : 8 of 200

Marks: +1, -0

4, 9, 19, ?, 79, 159, 319

Solution:

Concept:

The series follows the rule: multiply the previous term by

2

and add

1

Explanation:

4 \times 2 + 1 = 9

9 \times 2 + 1 = 19

So, the missing term is:

19 \times 2 + 1 = 39

Check the remaining terms:

39 \times 2 + 1 = 79

79 \times 2 + 1 = 159

159 \times 2 + 1 = 319

Answer:

The missing number is

39

Go to Question:

Prev Question

Next Question