Question

Find the missing terms to complete the given series.

1 2 3 3 5 5 7 7 9 11 ___ ____

• A. 11,13
• B. 12,13
• C. 11,12
• D. None of these

Answer 1

The correct option is A 11,13

We could not notice any common pattern in the above series On close observation we notice that it is a combination of two series We shall take the terms only at odd-numbered positions and analyse the pattern first
Now we shall take the numbers at even-numbered positions and analyse the pattern
2 3 5 7 11 ____
The terms are consecutive prime numbers Hence the missing number in this series is 13 which is the next prime number
This type of series is called twin series or combination/mixed series
Ans :- 11, 13.