Correct Answer - Option 2 : 10/3

**GIVEN:**

Triangular number = n(n + 1)/2 where n = 1, 2, 3

**FORMULA USED:**

Mean = sum of all the data/ Total number

**CALCULATION:**

When n = 1, 2 , 3 then triangular number = 1, 3 and 6

⇒ Mean = summation of all the number/Total number

⇒ Mean = (1 + 3 + 6)/3

∴ **Mean = 10/3**