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Select the number from among the given options that can replace the question mark (?) in the following series.13, ?, 25, 37, 53, 73

  1. A
    19
  2. B
    15
  3. C
    17
  4. D
    21

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 .

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Try it yourself before checking the explanation above.

Select the number from among the given options that can replace the question mark (?) in the following series.13, ?, 25, 37, 53, 73
A
19
B
15
C
17
D
21

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