Find the incorrect number in the series : 6,11,16,20,26……

Options

A. 20
B. 6
C. 26
D. 16

Answer

To find the incorrect number in the series: 6, 11, 16, 20, 26, we will analyze the pattern of the differences between the consecutive numbers.

**Step 1: Identify the differences between consecutive numbers.**
- The difference between 6 and 11 is:
\( 11 - 6 = 5 \)

- The difference between 11 and 16 is:
\( 16 - 11 = 5 \)

- The difference between 16 and 20 is:
\( 20 - 16 = 4 \)

- The difference between 20 and 26 is:
\( 26 - 20 = 6 \)

**Step 2: List the differences.**
The differences we calculated are: 5, 5, 4, and 6.

**Step 3: Analyze the pattern of differences.**
From the differences, we observe that the first two differences are 5, but the third difference is 4, which breaks the pattern. The expected difference should also be 5.

**Step 4: Determine the correct number.**
If the number after 16 should have been 21 (because \( 16 + 5 = 21 \)), then the series should have been:
6, 11, 16, 21, 26.

**Step 5: Identify the incorrect number.**
Thus, the incorrect number in the series is 20, as it should be 21 to maintain the pattern of adding 5.

**Final Answer:**
The incorrect number in the series is **20**.

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