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What is the average of all the natural numbers from 1 to 92?
47
46
46.5
47.5
46.5
For any consecutive arithmetic sequence (like natural numbers), the average is simply the midpoint of the first and last number: 21+92тАЛ=46.5.
First natural number (a) = 1, Last natural number (n) = 92, Total terms (N) = 92
Average=2First┬аterm+Last┬аtermтАЛ=2n+1тАЛ
For any consecutive arithmetic sequence (like natural numbers), the average is simply the midpoint of the first and last number: 21+92тАЛ=46.5.
Students often use 2nтАЛ=292тАЛ=46, forgetting that natural numbers start at 1, so the formula for the sum is 2n(n+1)тАЛ, which leads to an average of 2n+1тАЛ, not 2nтАЛ.
Identify the Given Sequence
The question asks for the average of natural numbers from 1 to 92. The sequence is 1,2,3,тАж,92. This is an Arithmetic Progression (AP) with first term a=1, last term l=92, and total terms n=92.
a=1,l=92,n=92
Recall the Sum Formula for First n Natural Numbers
The sum SnтАЛ of the first n natural numbers is given by the formula:
SnтАЛ=2n(n+1)тАЛ
Derive the Average Formula
Average is calculated as the total sum divided by the number of terms (n). Therefore:
Average=nSnтАЛтАЛ=n2n(n+1)тАЛтАЛ=2n+1тАЛ
Substitute n = 92 into the Formula
Substitute n=92 into the derived average formula 2n+1тАЛ:
Average=292+1тАЛ=293тАЛ=46.5
C is correct because substituting n=92 into the average formula 2n+1тАЛ yields 293тАЛ=46.5.
For any sequence in Arithmetic Progression (AP) where the difference between consecutive terms is constant, the average is always equal to the average of the first and last terms: Average=2First┬аTerm+Last┬аTermтАЛ.