The arithmetic mean of `1,2,3,...n` is (a)`(n+1)/2` (b) `(n-1)/2` (c) `n/2` (d) `n/2+1`

Explanation

To find the arithmetic mean of the series `1, 2, 3, ..., n`, we can follow these steps:

### Step 1: Identify the series
The series is `1, 2, 3, ..., n`. This is an arithmetic progression (AP) where:
- The first term \( a = 1 \)
- The common difference \( d = 1 \)
- The number of terms \( n \)

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