Question Details

Identify the incorrect term in the numerical sequence provided below.

6, 19, 58, 124, 214, 331, 474

Options

A

124

B

58

C

214

D

474

E

6

Show Answer

Correct Answer :

Option A

124

Solution :

The correct answer is 124.


To find the incorrect term in the numerical sequence, let us analyze the differences between consecutive terms in the given sequence:

6, 19, 58, 124, 214, 331, 474


Step 1: Calculate the first differences between consecutive terms.

19 - 6 = 13

58 - 19 = 39

124 - 58 = 66

214 - 124 = 90

331 - 214 = 117

474 - 331 = 143


Step 2: Identify the pattern in the differences.

Looking at the differences: 13, 39, ..., ..., 117, 143

Notice that 13, 39, 117, and 143 are all multiples of 26 apart (or multiples of 13):

13 = 13 × 1

39 = 13 × 3

117 = 13 × 9

143 = 13 × 11


The second differences between these valid terms are constant (equal to 26):

39 - 13 = 26

143 - 117 = 26


Therefore, the sequence of first differences should increase by 26 at each step:

1st difference: 13

2nd difference: 13 + 26 = 39

3rd difference: 39 + 26 = 65

4th difference: 65 + 26 = 91

5th difference: 91 + 26 = 117

6th difference: 117 + 26 = 143


Step 3: Reconstruct the correct sequence using the valid differences.

1st term: 6

2nd term: 6 + 13 = 19

3rd term: 19 + 39 = 58

4th term (correct): 58 + 65 = 123

5th term: 123 + 91 = 214

6th term: 214 + 117 = 331

7th term: 331 + 143 = 474


Comparing the given sequence with the correct sequence, the 4th term given is 124 instead of 123.


Hence, 124 is the incorrect term in the sequence.

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