Shortcut Trick Sum of the first 5 natural numbers = 5 × 3 = 15 New sum after adding the number 2 = 15 + 2 = 17 New total number of observations = 5 + 1 = 6 New average = 17 ÷ 6 ≈ 2.83 ∴ The correct answer is 2.83. Alternate Method Given: Average of the first five natural numbers = 3 The new number to be added = 2 Formula Used: Average = Sum of all observations ÷ Total number of observations Calculations: ⇒ The first five natural numbers are 1, 2, 3, 4, and 5. ⇒ Initial Sum = 1 + 2 + 3 + 4 + 5 = 15 ⇒ Total count of numbers initially = 5 ⇒ New Sum after adding the number 2 = 15 + 2 = 17 ⇒ New total count of numbers = 5 + 1 = 6 ⇒ New Average = New Sum ÷ New Count ⇒ New Average = 17 ÷ 6 = 2.833... ⇒ New Average ≈ 2.83 ∴ The correct answer is 2.83. Related Concepts: Average Formula Average = Sum of all observations ÷ Total number of observations. Sum of First 'n' Natural Numbers The sum of the first 'n' natural numbers can be directly calculated using the formula: S = n × (n + 1) ÷ 2. Combined Average When combining multiple groups or adding new values, the new average is evaluated as (Total Old Sum + New Values Sum) ÷ (Total Old Count + New Count).