Answers

2016-04-21T22:21:12+05:30
The number of terms is
N = (25 - 1) / 2  + 1 = 13
The sum of terms, which is the arithmetic progression with difference 2, is:
S = (1 + 25) × 13 ÷ 2 = 13 × 13
The average is:
A = S / N = 13 × 13 / 13 = 13

So, to calculate the average of arithmetic progression was needed to calculate the number of terms N, the average arithmetic progression is the average of first and last term:
A = (1 + 25) / 2 = 13
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