Select the number from among the given options that can replace the question mark (?) in the following series.13, ?, 25, 37, 53, 73
- A19
- B15
- C17
- D21
Solution & Step-by-step Explanation
Let's find the differences between the consecutive numbers given at the end of the series: The differences are , which form an arithmetic sequence increasing by each time.Following this pattern backwards, the differences before should be: Let's verify by checking the terms with these differences:First term = Second term = Third term = The terms match the given series () perfectly. Therefore, the missing number is .